Fragment handling for hash bang URLs

[lxbarth]

I just pushed a fix to fragment handling for hash bang URLs : 45becbc

Basically two things were broken:

• the override to Backbone.history.saveLocation()
• getFragment() stripped out the ! leading to mismatches of same URLs in checkUrl() (!/path != /path)

The fix brings extensive overrides to backbone which I'd rather avoid. The messiness stems from the fact that with hash bang (#!) URLs what's in the browser history (!/path) is different from the actual routes (/path) and thus non-JS fallbacks (http://example.com/path).