Config syntax

Breaking change updates to the config syntax.

`basic_auth` is now `auth` and accepts a string with `username:password`
uploader config options are now nested under the `uploader` key

See [README updates](https://github.com/carrot/roots-cms/commit/3e89e9ad2f2a74cfce348e603312bf951bad6fff) to see examples.

closes #29, closes #30