Allows a view to update the navbar title if his title changes

Added a watch to see if the contents of the view title changes and, if
so, fire an event to notify the navbar and update the title.
Added support for badges in TabBar icons.

Added support for TabBar icon badges using the attribute badge in the
tab directive.

Ex: <tab icon-on="icon ion-ios7-person" icon-off="icon
ion-ios7-person-outline" href="#/tab/myprofile" badge="3">

I’ve used the colors of the TabBar itself but inverted for the badge. I
don’t know if you’ll want to merge this straight on but I think it can
help as a start point for this feature. I’ve tried to do it as
integrated as possible.
Revert "Added support for badges in TabBar icons."

This reverts commit 1bd89a86f5f0ea972c0950f83ebf7857cd027b24.
Merge pull request #501 from uniring/nav-bar-title

Allows a view to update the navbar title if his title changes