log data only for valid worker ids
added test path for logging. https://github.com/browserstack/browserstack-runner/issues/65
Launching workers message printing twice
show filename only if there are multiple paths
delete workers on ctrl-c
Merge remote-tracking branch 'origin/bug_fixes' into pre_prod

Conflicts:
	lib/server.js
Merge branch 'cleanup' into pre_prod
Merge pull request #71 from browserstack/pre_prod

Pre prod