Replace twitter commons dirutil Lock with lockfile wrapper

Every now and then we see a pants process die without cleaning up its pidfile and subsequent runs in the same workspace hang forever.

This change replaces the twitter-commons dirutil.Lock with a thin wrapper around lockfile's PIDLockFile which prints the owner process commandline or breaks the lock if the owner process doesn't exist.

Testing Done:
https://travis-ci.org/pantsbuild/pants/builds/41821386

Bugs closed: 816

Reviewed at https://rbcommons.com/s/twitter/r/1390/