Issue #29 Pressing play while playing should restart the current track

- If already playing, use existing stop.
- Included underscore.js in project to make searching arrays easier. Can refactor to vanilla JS w/o library

Cheers
I thought keeping all things related to media functions should live in an object.

So, 
click -> handled by eventlisteners possibly something else to look at encapsulating
mediaService -> Help the eventlisteners by reducing code and duplicate logic and then also interface with the base 'Media' class to get stuff done