correctly mount tmpfs as /tmp in recovery

The syntax of init's mount command changed in April 2008 but
recovery's init.rc was never updated, so recovery's /tmp has been on
the root fs all this time.  Fix.

Also add /system/bin to the PATH in recovery, which is handy for
debugging.

Change-Id: I9e60d18803906bc75c263f12c8863cfd6a14147b
Merge "correctly mount tmpfs as /tmp in recovery" into android-4.4