Move checkbox into navbar

This issue has been migrated from mozilla/webmaker-android#1911.

It was originally written by gvn on Tue May 19 2015 and had the following description:

We need to move the placeholder HTML button into the Android navbar for Project Settings.

On Tue May 19 2015, thisandagain commented:

I'm likely not going to be able to get to this during this sprint. Can we add a button within the webview or automagically trigger the PUT to the API?

On Tue May 19 2015, gvn commented:

Yep, there's another ticket to wire it up to the backend: mozilla/webmaker-android#1909

This is just to finish up the design-end of things, but not a functional blocker! :+1: