Font-awesome cache busting params

[juggy]

This issue is related to https://github.com/martndemus/ember-font-awesome/issues/64

It seems the cache busting params (?v=4.7.0) that font-awesome uses avoid the font files from being properly fingerprinted. Since font awesome is distributed that way, we cannot change the params.

(if there was a previous issue on this please link it to me so I can have a look.)