[MIE-721] Changed "track" method to track in GTM if it exists and/or GA if it exists

Related ticket: 

https://ngjira.nationalgeographic.com/browse/MIE-721.

Check a given event, can be tracked with Google Tag Manager by checking if the variable "dataLayer" exist. If it's possible, will push the item to dataLayer.

Check a given event, can be tracked with Google Analytics by checking if the variable "_gaq" exist. If it's possible, will push the item to _gaq.