Add overrides.scss, hiding main-content-header.
WIP: Display dummy annotation script during video playback.
Merge branch 'master' into annotations

Conflicts:
	src/cljs/raiseyourgame/lib/youtube.cljs
	--> Resolved keeping master changes and restoring
	    mysteriously lost on-timecode function.
Move timeline.cljs to correct CLJS source path.
Let timeline proof of concept work with youtube/on-timecode.
Display annotation only if playhead has reached it.

In the proof of concept, we just displayed the annotation closest to the
playhead (i.e. the current timecode). Now we will display the most
recent one that the playhead has reached -- with nicer-looking logic.
Update compass/config.rb for new static path; add fontawesome files.
Shrink global nav; kill whitespace below nav in video view.
Hide video description when annotation display begins.