Merge pull request #5 from stephen-soltesz/master

Add message to 'drac.py reboot' suitable for sending to ops@ mailing list
add user syncing & rename 'pi_list' to 'user_list'
Merge pull request #6 from stephen-soltesz/master

update M-Lab operator list, and handle failures due role mismatch a little better
add note regarding createusers behavior
Merge pull request #8 from stephen-soltesz/sync-users

Support syncing list of users & change 'pi' to 'users'