Code format using new elixir code formatter

[kartikjagdale]

1. Format lib folder and test folder
2. Added formatter so you can format entire app without specifying the file names
   see Format auth_controller.ex #189

[jwworth]

This is really cool; thank you for contributing! ❤️

We have stopped autoformatting files as described in #189 for now. Until we can run Elixir 1.6 on CI, something I anticipate working well when it's officially released in 2018, we will have no way to enforce these changes on future pull requests.

When we have that guarantee, we'll be only be changing a few files a time, to review and make sure they improve the code and don't break anything. Feel free to open a smaller (1-2 files or a directory) then.

For now we can merge the formatter config file, if you're interested in a smaller PR. Thanks!