Add admin check before trying a remote wipe

* The code assumed that if we asked for a remote wipe, that it would
  be executed.  This isn't the case, however, if we're not a device
  admin at that time
* Test for Email app as device administrator before trying remote wipe

Bug: 2603931
Change-Id: I09dcff00e77bcf1e40c742c9dee923e6e07eecae
1 file changed