Make /cache/recovery/last_log available in recovery

Create a new recovery UI option to allow the user to view
/cache/recovery/last_log for their device. This gives enhanced
debugging information which may be necessary when a failed
OTA occurs.

Bug: 18094012
Change-Id: Ic3228de96e9bfc2a0141c7aab4ce392a38140cf3
3 files changed