Support -s in installmod command

The -s flag must be passed before the adb command,
as in `adb -s emulator-5554 install myapp.apk`
instead of `adb install -s emulator-5554 myapp.apk`.
Parse it and move it to the correct location if it
exists.

Test: Manually
Change-Id: I4b296d7fe4efbe3b25d21d33a8082b321787651a