Turned suite run directory into a rolling archive.

Re-running a suite will not overwrite existing log files.
Just warn if site or user config parsing fails.

If the site config file is broken it will not prevent users from running
suites if the cylc defaults or their user config file is sufficient.
Disable by default, and warn about Rose compat.
Replaced sys.exit with raise exception.
loadleveler job name: prefix with suite name.
Merge pull request #454 from hjoliver/relax-site-user-config

Just warn if site or user config parsing fails.
Merge pull request #457 from matthewrmshin/llsubmit.suite.task

loadleveler job name: prefix with suite name.
Nicer error message.
Make test-battery command compatible with previous change.
Merge pull request #455 from arjclark/db-rogue-exit

rundb: replace sys.exit()
Merge pull request #453 from hjoliver/run-dir-rolling-archive

Turned suite run directory into a rolling archive.
cylc.job_submission.loadleveler: fix import.
Merge pull request #458 from matthewrmshin/loadleveler.fix

cylc.job_submission.loadleveler: fix import.