[IMP] update fontawseome to 4.0.3
[REM] gravatar support
[IMP] upgrade backbone to 1.1.0
[FIX] breakage due to backbone change: in 1.0+, this.reset() will call this.add()

in 0.9, this.add would only be called if items were provided to
reset(), changed in commit cf6e862.
[IMP] add warning re. changed behavior of backbone which may be changed in the client