On sync, change only posts/pages that are synced

We should never overwrite a post with server content it it's either
Pushing or Failed, or else we can lose the user's data

fixes #1545

git-svn-id: http://ios.svn.wordpress.org/trunk@4004 7d847f7c-ffe1-4a24-85be-b788d016d96a
Removed unused method for notifications stats, since we're going to record those stats server side.

git-svn-id: http://ios.svn.wordpress.org/trunk@4005 7d847f7c-ffe1-4a24-85be-b788d016d96a
Add the app version number to the parameters sent in wpcom.mobile_push_set_blogs_list.

git-svn-id: http://ios.svn.wordpress.org/trunk@4006 7d847f7c-ffe1-4a24-85be-b788d016d96a