Crop wallpaper and lockscreen images before saving them

Images were saved as-is and could cause large heap usage when
Wallpaper loads them later. This patch crop the images to fit the
screen size before saving them (as wallappper cropper activity does)

Change-Id: I08c04d9d14a65355c4417f0414d7a6ac538b3ea0
Merge remote-tracking branch 'cyan/cm-11.0' into cm-11.0