added enable option to disable gerrit plugin in sonar

Change-Id: I7a89ebf7df6ce2bd11ffd985ba53d5f51c0c179f
sonar rule correction

Change-Id: I9a0afafeecd8baed9b6f6ade4ede6ff3c2920abf
reworked configuration

Change-Id: Id49409f14e36ba25d32b1b81b699ec96f757d21f