silent_socket.py writes status info to stdout
silent_socket.py does not print its PID on startup
refactor spawning of background service
kill the background service a bit more gracefully :o)
TEST: failover on 404 error
FIX: test 021 failed since cvmfs now unmounts itself
TEST: failover on 404 error on root catalog
TEST: failover to seperate replica if data chunk is missing
TEST: failover to separata replica if data chunk is corrupted
TEST: failover to separate replica if manifest file is corrupt
Some more Failover Tests