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
Merge pull request #113 from Logan676/lg2

allow to use mobile network to backup photos