email tracking with GA - POC

##### Email Opens:
### Event Test Endpoint: 
https://ga-dev-tools.appspot.com/hit-builder/

### Creating GA query properties:
Unique Member ID, Message ID, Message Network & Message Content

From Admin > Custom Definitions > Custom Dimension(order sensitive), create these properties as dimensions(see article https://support.google.com/analytics/answer/2709829)
The resultant properties with the the keys: cd1, cd2, cd3 & cd4. These will be used in the event hit.

### Event Hit Summary Example:

POST /collect HTTP/1.1
Host: www.google-analytics.com

v=1&t=event&tid=UA-118875082-1&cid=23324&ec=email&ea=open&el=facebook%20credentials%20expiring%20for%20vicgoburg%40gmail.com&cd1=1&cd2=3&cd3=facebook&cd4=some%20message

### In rails: 

@google_analytics_url = “http://www.google-analytics.com/collect?v=1&t=event&tid=UA-118875082-1&cid=#{@user.id}&ec=email&ea=open&el=#{ERB::Util.url_encode(‘credentials expiring’)}&cd1=#{@user.id}&cd2=#{}&cd3=#{authentication.platform_display_name}&cd4=#{}”

`N/B` All values sent to GA must be both UTF-8 & URL Encoded

### Embedding Analytics in Mailer:
<img src=<%= @google_analytics_url %>/>

##### Email Click Tracking:
Using utm parameters https://ga-dev-tools.appspot.com/campaign-url-builder/
Note: The email should have links back to your website or app. We recommend tagging the links with campaign parameters

### Postface
An update needs to be made to GaggleAMP-patrol https://github.com/GaggleAMP/Patrol/blob/master/lib/patrol/tracking_server.rb
to send hits/click tracks to GA.