cleaning up lint warnings and errors

gistfile1.txt

1. For paddingStart, Severity: Errors.
   because we also have paddingLeft, so for old platform, the paddingStart is ignored; so api < 17, the lint tool 
   will show error about paddingStart, and we do not currently support RTL, and paddingStart work the same way as 
   paddingLeft, so i think it really about the NewApi. Because the lint tool just check whether paddingStart is 
   compatible with api < 17, and I check that when api == 16, it works fine and does not crash. I have checked all
   the lint error list, i do not find other lint checks might solve this. So I think just add 
   tools:ignore="NewApi" will be fine. 
   
2. the warnings in build.gradle showing that some of the tools are using the old version, do i need change 
   these to newest, or just suppress lint to ignore NewerVersionAvailable.
   
3. for negative margin wawrnings in the code,
   /ta-flights-android/TAFlights/src/main/java/com/tripadvisor/android/taflights/views/FlightSearchItemView.java:154: 
   Error: Call requires API level 21 (current min is 14): android.widget.TextView#setLetterSpacing [NewApi]
   i just use @SuppressLint("NewApi"), the error shows negative margin is avaiable in api 21, but i think it is not the reason; 
   
   For negative margin in the xml, 
   ta-flights-android/TAFlights/src/main/res/layout/fragment_airport_list.xml:14: Warning: Margin values should 
   not be negative [NegativeMargin]
   i use tools:ignore="NegativeMargin".

4. About RelativeOverlap warnings:
  /ta-flights-android/TAFlights/src/main/res/layout/flight_search_result_item_row.xml:26: Warning: 
  @id/marketing_airline_name can overlap @id/price if @id/price, @id/marketing_airline_name grow due to localized text expansion [RelativeOverlap]
        <com.tripadvisor.android.taflights.views.RobotoTextView
        ^
 /ta-flights-android/TAFlights/src/main/res/layout/leg_details_layout.xml:58: Warning: @id/airline_name_text 
 can overlap @id/amenities_view if @id/airline_name_text grows due to localized text expansion [RelativeOverlap]
        <com.tripadvisor.android.taflights.views.RobotoTextView
        ^
 /ta-flights-android/TAFlights/src/main/res/layout/leg_details_layout.xml:197: Warning: ImageView-5 can overlap 
 @id/warning_icon if @id/leg_warning_text grows due to localized text expansion [RelativeOverlap]
            <ImageView
            ^
 /ta-flights-android/TAFlights/src/main/res/layout/outbound_summary_row.xml:35: Warning: @id/marketing_airline_name 
 can overlap @id/outbound_date if @id/outbound_date, @id/marketing_airline_name grow due to localized text expansion [RelativeOverlap]
        <com.tripadvisor.android.taflights.views.RobotoTextView
        ^
 /ta-flights-android/TAFlights/src/main/res/layout/search_result_header.xml:94: Warning: @id/travel_date_text_view 
 can overlap @id/travel_place_text_view if @id/travel_place_text_view, @id/travel_date_text_view grow due to localized text expansion [RelativeOverlap]
        <com.tripadvisor.android.taflights.views.RobotoTextView
        ^
 /ta-flights-android/TAFlights/src/main/res/layout/search_result_header.xml:126: Warning: @id/baggage_disclaimer_text_view
 can overlap @id/itinerary_summary if @id/itinerary_summary, @string/flights_app_baggage_fees_cbd grow due to localized text expansion [RelativeOverlap]
        <com.tripadvisor.android.taflights.views.RobotoTextView
        ^
 /ta-flights-android/TAFlights/src/main/res/layout/simple_list_item_checkbox_2.xml:22: Warning: @id/text1 can
 overlap @id/check_box if @id/text1 grows due to localized text expansion [RelativeOverlap]
    <com.tripadvisor.android.taflights.views.RobotoTextView
    ^
   For click_to_call_banner_row.xml, change RelativeLayout to Linearlayout
   For search_result_header.xml, add tools:ignore="RelativeOverlap"
   For outbound_summary_row.xml, add tools:ignore="RelativeOverlap"
   For leg_details_layout.xml, add tools:ignore="RelativeOverlap"
   For flight_search_result_item_row.xml, add tools:ignore="RelativeOverlap"
   
5. For overdraw warnings, i think add the suppressLint("Overdraw") will be fine; Or improving the performance by:
   http://stackoverflow.com/questions/11994454/possible-overdraw-root-element-paints-background
   http://stackoverflow.com/questions/9195762/possible-overdraw-root-element-paints-background
   second solution might need to change the source code.

6. Warnings /ta-flights-android/TAFlights/src/main/res/drawable-xxhdpi: Warning: Missing the following drawables
   in drawable-xxhdpi: ab_stacked_solid_flightstheme.9.png, cab_background_bottom_flightstheme.9.png, 
   cab_background_top_flightstheme.9.png [IconDensities]
   these *.9.png files are missing in the drawable-xxhdpi, http://stackoverflow.com/questions/17364394/android-graphics-for-xxhdpi
   so if we want do this, we can add these files into drawable-xxhdpi, otherwise just add the suppressLint("IconDensities")
   

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7. ta-flights-android/TAFlights/src/main/java/com/tripadvisor/android/taflights/views/LetterSpacingTextView.java:35: 
   Error: This method is not overriding anything with the current build target, but will in API level 21 (current target is 19): 
   com.tripadvisor.android.taflights.views.LetterSpacingTextView#getLetterSpacing [Override]
    public float getLetterSpacing() {
                 ~~~~~~~~~~~~~~~~
   public void setLetterSpacing(float mLetterSpacing) {
               ~~~~~~~~~~~~~~~~
   These two methods are added in API 21, it might override after the target API is 21, so we can add @SuppressLint("Override")for now
   and if we change the target API in the future we can rename these method