Upgrade mousetrap

Mousetrap now supports overriding stop behavior instead of us having to
hack it (via Mousetrap.stopCallback).

Also, it fixes a shift-F issue in inputs since newer mousetrap has
better input detection.
Make escape blur inputs

This effectively makes a 'normal mode' feeling by allowing you to
always get out of the other modes.

Especially effective if you don't use a modifier key to prefix commands.
Fake an 'insert mode' by pressing 'i'

Really, it is just a user-requested way to stop actions from happening.
Restore previous input behavior w/ modifiers

Previous to the last mousetrap upgrade, when using a modifier key to
prefix commands, these commands were available even inside inputs. This
behavior was lost when mousetrap was upgraded to 1.3.

This commit restores that behavior.
Merge pull request #13 from woahdae/modes

Add 'normal mode' and 'insert mode' behavior