support version 2 (2048-bit e=65537) keys in recovery

Signed-off-by: Chirayu Desai <cdesai@cyanogenmod.org>
Change-Id: I9849c69777d513bb12926c8c622d1c12d2da568a
Merge pull request #1 from CyanogenMod/cm-10.1

support version 2 (2048-bit e=65537) keys in recovery