Create config.json linter

[cmccandless]

It would be nice to have Travis-CI check the formatting of config.json for pull requests so that maintainers don't have to micromanage edits to that file. This could be accomplished by adding a script config.py (happy to take suggestions on the name of this file) that supports the following sub-commands:

• add
  • Creates a new entry in config.json for the specified exercise
• edit
  • Makes changes to existing exercise entry in config.json
• remove
  • Remove specified entry from config.json
• deprecate
  • Marks the exercise as deprecated in config.json
• lint
  • Checks the exercises in config.json for style violations, using either a hard-coded format, auto-detecting format using the first exercise as a template (more trivial than it sounds), or some combination of the two. This would be called by Travis-CI.

I actually already have a script that does most of the above, and could easily be modified to support the lint subcommand.

[kytrinyx]

@cmccandless This would be useful across the board for all Exercism tracks. I'd suggest opening this issue in the Configlet repo so that we can implement it into the tool that we already use for config-related linting and formatting.

[kytrinyx]

Let's go ahead and close this one in favor of exercism/configlet#117 🎉