Submodules: Updating submodules to API 18

Please refresh your local submodules by running "git submodule update -f"

I had to update both submodules again so we stof have some compile warnings. These where the changes:
https://github.com/DroidPlanner/usb-serial-for-android/commit/760913c568249f3a3459d7290fde311d06bb6b52
https://github.com/DroidPlanner/HorizontalVariableListView/commit/06990ce44b1c33820b0bed828975171d77ef45e0