Storage Settings: Allow user to trigger a volume rescan

This change allows to trigger a rescan of a volume with the next restrictions:
- Internal volumes if they are emulates
- Primary volumes
- Non-Removable volumes

Ported from: http://review.cyanogenmod.org/44586

Change-Id: I7e75a324938d8081fd715f702d50f1fdceabd96d
Merge "Storage Settings: Allow user to trigger a volume rescan" into cm-11.0
Merge remote-tracking branch 'cm/cm-11.0' into cm-11.0