Added the ability to turn off push notifications for a fix period of time. Removed the shortcut to turn off all blogs for now. We need to find a better UI for it.

git-svn-id: http://ios.svn.wordpress.org/trunk@4085 7d847f7c-ffe1-4a24-85be-b788d016d96a
Changed the key of the mute setting value to 'mute_until'. props @kokejb.

git-svn-id: http://ios.svn.wordpress.org/trunk@4086 7d847f7c-ffe1-4a24-85be-b788d016d96a
Fix typo

git-svn-id: http://ios.svn.wordpress.org/trunk@4087 7d847f7c-ffe1-4a24-85be-b788d016d96a