wallpapercropper: OOM issue while opening *.bmp image

This change manages setting of large images as
wallpapers without encountering OOM.

CRs-fixed: 619815
Change-Id: I3a32ec4b42050b146076f0adf6b6e65afd6fae4e

Conflicts:
	packages/WallpaperCropper/src/com/android/wallpapercropper/WallpaperCropActivity.java