[v6r11] Minor fixes

FIX: FC.Utilities - treat properly the LFN names starting with /grid ( /gridpp case )
FIX: import gMonitor from it is original location
FIX: StalledJobAgent - extra checks when failing Completed jobs, closes #1944 
FIX: LocalConfiguration  - added exitCode optional argument to showHelp(), closes #1821
FIX: JobState - added protection against absent job in getStatus(), closes #1853