Android: Improve permissions handling
Android: Improve permissions handling

By default, xwalk_android_permissions from manifest.json are added
to AndroidManifest.xml with a namespace of android.permission. But
if permissions already have a namespace, keep it, and do not add
the android one too.

BUG=XWALK-6214

baleboy/crosswalk-app-tools,baleboy/crosswalk-app-tools,crosswalk-project/crosswalk-app-tools,baleboy/crosswalk-app-tools,crosswalk-project/crosswalk-app-tools,crosswalk-project/crosswalk-app-tools