Establish basic extension system

[alexcabrera]

Being able to extract common patterns into something that could be used across proto projects would be useful. Think of reset stylesheets, icon sets, etc.

These extensions could be saved in a ~/.proto directory and might be able to be structured similarly to proto projects.

The command line interface could looks something like this.

proto -r reset flatstyles -i testproj

[alecperkins]

I've been thinking about this in terms of templates, which would just pre-fill proto projects with settings and content. Something like proto -t mobile -i project. Syntax seems a little verbose though. Reference/includes might be better, but more complicated to manage.

[alecperkins]

A simpler template system might be to have a set of Gists that are named and the mapping of names to IDs is included in the CLI. That way, the templates themselves can be kept out of the codebase and just use the Gist loading capability. So, proto -it <template_name> to initialize and proto --list_templates to list the available templates.

[alecperkins]

Goes hand-in-hand with #18, a proper remote-project management scheme.