Don't stash cropped photos in /sdcard/DCIM.

Every time we choose a new contact photo (either an existing one from
the gallery or a new one from the camera), we write the cropped image
/sdcard/DCIM.  As a result, the cropped image (eventually) appears in
the gallery, is uploaded to G+, etc.

The new behavior is to write the cropped photo to a temp directory,
and to clear it when we're done with it.

Revert some of the changes from Ib7037a66; we still need to persist
properties in onSaveInstanceState() in case ContactEditorFragment is
killed while the user interacts with the camera/gallery.

Bug: 6423139
Change-Id: Icf8cb5b4824e3d8757ff483ef128527ac9132e72