Require redcarpet >= 3.1.1 for yard docs.

This is needed because version 3.0.0 throws an error when trying to
generate docs.

Change-Id: I27af3c466087ea8f2e28be3bc86b411e2bf62248
Don't fail log spec on Faraday version mis-match.
Update order of params in stub to fix specs.

Seems like Faraday 0.9.x has changed something to do with order of params,
so this fixes specs by updating the stub url's to what it expects.
Support for auth header and form encoded params.

Initial commit to add oauth authorization header with token to requsts.
Also adds call to request an auth token given cliend id and secret.
Add AuthenticationException for incorrect auth.

Thrown on invalid credentials to get_auth_token, or if auth_token not
accepted on client calls.
Make get_auth_token work in mock mode.
Update README for auth_token config and new call.

Added info on how to pass auth_token to configuration and example of
get_auth_token call.
Merge pull request #1 from freerunningtech/oauth2-support

Add authorization header support and call to generate auth token.