adb: handle adbd auth in recovery mode

If /data/misc/adb/adb_keys exists, copy it to /adb_keys, set property
for secure adb, and restart the adbd daemon.

Change-Id: I2f826d4c1f6a49cb0959c9cd1a803cb10ec4e408
Merge "adb: handle adbd auth in recovery mode" into cm-10.1
Merge remote branch 'cm/cm-10.1' into jb