tests: Fixed start and stop methods in xstartserv. Now waitpid() is only used to cleanup any zombie processes while /proc/<pid> is checked if the process does run.
tests: Fixed start and stop methods in xstartserv. Now waitpid() is only used to cleanup any zombie processes while /proc/<pid> is checked if the process does run.

gurkerl83/millipede-xtreemfs,gurkerl83/millipede-xtreemfs,gurkerl83/millipede-xtreemfs,gurkerl83/millipede-xtreemfs,gurkerl83/millipede-xtreemfs,gurkerl83/millipede-xtreemfs,gurkerl83/millipede-xtreemfs