Fix activity stack when restarting the screen nail

We were stacking multiple activities, resulting in the need for multiple
destructions (back key events) when killing the camera app

Change-Id: I7ec61c517d25f7e47baf47fcd1696f987631c344
Gallery : Filter picasa specific options

Remove menu options that don't serve a purpose due to their dependency
on picasa support being built in.

Also add in the help url to stay in sync with GalleryGoogle.

https://jira.cyanogenmod.org/browse/CYAN-1329

Change-Id: Ie75b839ec9b30a5a934477e92523803239a238e3