improved exit codes to comply with LSB
improved exit codes to comply with LSB

Changed the exit codes returned by the init script to comply with LSB recommendations.
Added constants with the exit codes

reconfig and upgrade in frontend/factory were returning:
- stopped, reconfigured and started: 0/0
- reconfigured a stopped service: 0/0
- failed to stop (if initially running): 1/1
- failed to reconfigure (even if started with old configuration): 1/1
- failed to start (after stopping and reconfiguring, even if reconfigure failed): 1/1

The new behavior is similar except:

If not installed (start or check executables missing) fail exit code: 5   (before was 1 because invocation failed)

reconfig and upgrade in frontend/factory are now returning:
- failed to reconfigure (even if started with old configuration): 6/6
- failed to start (after stopping and reconfiguring, even if reconfigure failed): 1/1
To comply with LSB suggestions (1 was OK but 6 is better)

bbockelm/glideinWMS,bbockelm/glideinWMS,bbockelm/glideinWMS,bbockelm/glideinWMS