Allow cancelation of adb sideload.

Change-Id: I1cc5a6719c3fe547afe944a94e134519c2c45fc6
allow sideload to be triggered via /cache/recovery command for eat

Change-Id: I36996ceea831160830815c1b267328f307bbd906
Merge branch 'cm-10.1' of github.com:CyanogenMod/android_bootable_recovery into cm-10.1