Gallery2: make panoramic focus mode configurable

 - This allows for device maintainers to switch between
   INFINITY and CONTINUOUS_VIDEO focus modes.  Some devices
   do not support INFINITY so the image and preview are both
   out of focus.

Change-Id: I81a69c7e9ce55037184ee7edd755f8c88507f781
Merge branch 'cm-10.2' of github.com:CyanogenMod/android_packages_apps_Gallery2 into cm-10.2