Backend+AK2: misc fixes

- fix fallback broken unzip detection now that we create a subdirectory prior
- probably best to execute the bump/loki/whatever script using our included ash shell instead of the recovery sh.

META-INF/com/google/android/update-binary

@@ -30,7 +30,7 @@ ui_print " ";
 mkdir -p /tmp/anykernel/bin;
 cd /tmp/anykernel;
 unzip -o "$ZIP";
-if [ $? != 0 -o -z "$(ls /tmp/anykernel)" ]; then
+if [ $? != 0 -o -z "$(ls /tmp/anykernel/tools)" ]; then
   abort "Unzip failed. Aborting...";
 fi;