Added uitests-kill_app

to kill an app and stop tcpdump
Added app_name.txt file on each project

+ added get_app_name.sh script to generate them
Utils: launch only one tcpdump and dump both ifaces

+ when stopping tcpdump, remove the .pid file
launch_tests: force rebuild if local.prop file is missing
launch_tests: launch: if not success, remove useless traces
launch_tests: support uitests-kill_app

kill the app and tcpdump after each launch (even if there were an error)