Revamped Advanced File Upload fields

The `file_advanced` and `image_advanced` fields now use the
`underscore.js` library to create new items on the client side.
Misc tweaking with color and taxonomy
oEmbed Tweaking
Field creation logic now in a seperate function.

Prep work for field groups
Fixing bugs
show_fields fixes
Merge pull request #292 from funkedgeek/master

File and Image advanced now use Underscore.js