optionally autokill nailguns
Merge pull request #17 from tinystatemachine/master

Option to automatically kill nailguns before exiting
Release the lock before running tests.
Fix bug in dependency checking.

Auditors: markcc
Ignore .pids dirs.
Merge branch 'master' into new_reporting

Conflicts:
	src/python/twitter/pants/commands/goal.py
	src/python/twitter/pants/tasks/jvm_dependency_cache.py