Pylabs: Return exit code of 'start', 'restart' and 'catchupOnly' invocations

See: ARAKOON-383
See: http://jira.incubaid.com/browse/ARAKOON-383
See: ARAKOON-379
See: http://jira.incubaid.com/browse/ARAKOON-379
Merge pull request #45 from Incubaid/ARAKOON-383

Pylabs: Return exit code of 'start', 'restart' and 'catchupOnly' invocations