Allow non datamedia devices to wipe encryption

With 5.0 L, we decrypt automatically if the default_password is
used. Non datamedia devices do not get the format data button so
they cannot wipe encryption off the device. This patch add a wipe
encryption button where the format data button would normally be
located on the Wipe page.

This patch also attempts to remove / delete the dm-crypt block
device before formatting.

Change-Id: I100d5d154d6c49254fd48e23279df973db5f23ae