Add deployer info to lock file and flake8/pep8 fixes

* On aborts, check to see if another user started the deploy and
  require --force if so.
* On start, if a deployment is already underway, tell the user
  who is currently holding the lock.
* pep8/flake8 fixes
Open lockfile for reading properly and close it
Better error checking for lock file open and close
Format the abort error message with the user
Better message for abort
Merge pull request #3 from lyft/lockinfo

Lockinfo