Use okhttp 1.3.0.

- https://github.com/square/okhttp/blob/master/CHANGELOG.md.
Use retrofit 1.4.1.

- https://github.com/square/retrofit/blob/master/CHANGELOG.md
Start next dev cycle.
Use .setEndpoint() instead of .setServer().

-
https://github.com/square/retrofit/blob/master/CHANGELOG.md#version-140-2014-01-31
Take more precaution when handling access token response.

- Error streams can be null.
- Throw OAuthSystemException instead of catching IOException.