allow to use mobile network to backup photos

by default only use WiFi to backup photos.
always use WiFi when both network types available.
translate words into Chinese
turn on/off camera upload service under any network state

change to always allow user to turn on/off camera upload service
under any network state
source cleanup
code cleanup
keep camera upload service alive

when user cancelled selecting library, keep service state as it was before
code cleanup
fixed gesture lock
Merge pull request #113 from Logan676/lg2

allow to use mobile network to backup photos
center-horizontally position account list items
add account list footer

center-horizontal footer (the button)
change dialog style and button style

center-horizontally position these controls
change controls color to orange
customize checkbox layout
code cleanup
code cleanup
supporting multiple screens

1. add layout-sw600dp to support 7” tablets (600dp wide and bigger)
2. add layout-sw720dp to support 10” tablets (720dp wide and bigger)
Older versions of the platform will ignore the new qualifiers,
so we should mix them as needed to ensure the app looks great on any device
we can do like below
3. add layout-xlarge to support pre-3.2 tablets, and
layout-sw600dp to support 3.2 and up tablets.

FYI, http://developer.android.com/about/versions/android-3.2.html#api.