transceiver: fix check for existence

The transceiver check if it is already running when initializing.
However, this check was done by comparing its pid for >= 0, which is not
sensible anymore since valid PIDs only start at 1.
Merge pull request #1602 from OlegHahm/transceiver_init_pid_check

transceiver: fix check for existence
tests: enable cppcheck for PR in travis
SQASHME: move to script
SQUASHME: unify files to check
SQUASHME: make it possible to pass options