add getUserBinCount to db adapters
supply the view with the user bin count
Simplified navigation UI

- Changed avatar to open profile menu
- Change "open" to "My bins" and "JS Bin" to "Bins"
- Hoping users will actually find how to get to their history...
Merge branch 'master' into fix/avatar-as-menu-655

Conflicts:
	lib/handlers/bin.js
	lib/models/user.js
Merge pull request #657 from remy/fix/avatar-as-menu-655

UI: Change avatar to menu