bluetooth: allow sending bugreports via bluetooth

Bluetooth can receive bugreport data for beaming to another device.
This comes across as an open file descriptor. Allow bluetooth access
to bugreports.

Addresses the following denial:

  avc: denied { read } for path="/data/data/com.android.shell/files/bugreports/bugreport-2014-12-19-15-35-32.txt" dev="dm-0" ino=662738 scontext=u:r:bluetooth:s0 tcontext=u:object_r:shell_data_file:s0 tclass=file permissive=0

Change-Id: I7be2ce2e0e48323c1e8f932be17b434b89daf085