retrieve PID from util.cc:ManagedExec on demand
hand child PID through util.cc:ExecuteBinary on demand
wait 5 seconds for gdb to terminate, then finish it with the big hammer kill -9
adapt stacktrace testcases to wait long enough for the stacktrace creation
added note to ChangeLog
Merge branch 'kill_gdb' of git://github.com/reneme/cvmfs into reneme-kill_gdb

Conflicts:
	ChangeLog
cosmetics
fix subtle bug in ManagedExec