Redo templates with docs and whatnot

This totally breaks compatibility with rebar2, and maybe it shouldn't
have.

Double-check it or something before I shove this in.

This should also be followed by an update to the plugins documentation to use the template to create the plugin for simplicity's sake.

I think I also forgot to maintain support for the `-f`/`--force` support to overwrite existing files, which might need to be added.