lesson-6-challenge

Overall functionality:
mostFrequentWord(string) --> @return: returns the word that appears the most in a given string;

First, function calls a getTokens(text) method on some string 'text'.
This getTokens method returns an array of the words found in the string passed as an argument transofrming all
characters to lower case, using any numbers of white space, commas, exclamation points, periods, quotation marks,
semi-colons, colons, or dashes in any frequency as the delimiter to determine where each word begins/ends, removes falsy
items and sorts the words alphabetically.  
--> tl:dr strips just the words consisting of letters A-Za-z9-0 into an array

After parsing all words from string into an array called words
it declares a wordFrequencies object

it then iterates through every member (word) of the words array 
and 
if the word is already a key 
of the wordFrequencies object, it updates its value (count) by 1.
if word is not already a key, it adds the word (key) with a value (count) of 1.

Then, it sets a variable to keep track of the word with the highest count setting the base value as the first word (key)
of the wordFreq object with its corresponding value.

It then uses a for loop to iterate through every key in wordFreq obj and references that key
as 'word'
if that words count is higher than the current maxCount
  it sets the currentMax as 'word'
  and sets the current max count as the 'word's count value
  this repeats until all key/value pairs in wordFreq object have been compared against current max key/value variables

Finally returns the word found to have the highest count based on algorithm above