RFC: Initial spike on as-service architecture

This pull request continues the work started in strongloop/loopback-example-access-control#5.

The most significant change is the move from a loopback plugin generating javascript on runtime to a more service-like approach, where we are providing a command-line tool for generating a static services file. This way it will be easier to integrate the generated services file into a minification & bundling workflow (e.g. via Grunt) too.

The generated file includes basic documentation comments based on remote method definitions provided by LoopBack app.

See README.md in the branch for instructions on how to use this new module.

/to @ritch @seanbrookes @Schoonology Please review the solution, whether it's easy to use, also the overall implementation design. There's no need to nit pick about implementation details, most of the code will be thrown away.

/cc @altsang