Tech - Team Shotgun: Add option to allow a prefix config [#56508038]

Pivotal tracker story [#56508038](http://www.pivotaltracker.com/story/show/56508038) in project *Tech - Team Shotgun*:

> Currently we do not allow a easy to prefix our lock keys. This brings up a problem because if we deploy this on staging we would like to have our keys namespaced by their environment. 
> 
> Change the remote lock gem to allow a config option. 
> 
> End up this story by submitting a PR, after it gets merged, deploy to a staging server and let me know.