Refactor the code in the strings face and extract much of the functionality
into a separate library in order to make the code more readable and
sustainable. Additionally, remove the `modules` action from the face
since it does not have a clear use case currently. However since the `server`
action depends on it, and it may be helpful to add other features in the future,
extract the functionality previously contained in `modules` into a helper
method.
Prior to this commit, the handlers and code objects which dealt with
puppet functions were referred to as `FutureParserFunctions` and
`ParseFunctions`. This naming convention will not make very much
sense going forward when the future parser becomes the primary
parser. Therefor, rename `FutureParserFunctions` to `Puppet4xFunctions`
and `ParserFunctions` to `Puppet3xFunctions`.
Hailee Kenney