We were already compiling the markdown bundle via ember-cli, but that version was only being used in the test environment. This commit improves the implementation, and updates the filename so it's also used in production.
This commit also
- Removes the vendored copy of `markdown-it.js` and fetches from node_modules instead
- Updates `pretty_text.rb` to remove the custom sprockets-manifest-parsing
- Removes `pretty-text-bundle.js`, which was only being used by `pretty_text.rb`
* DEV: Use custom tags rather than handlebars server side
These will be skipped if they are ever rendered in a document. The
handlebars really messes stuff up.
* DEV: Build our own locale file for testing purposes
We can't practically proxy everything in test mode, but we can
approximate the logic and build our own locale file for testing purposes
that works quite well. This allows us to run tests without a proxy.
* DEV: Support for testem runner for ember cli tests
