Push version to 3.2.1.
Update to retrofit 1.6.1.

- https://github.com/square/retrofit/blob/master/CHANGELOG.md#version-161-2014-07-02
Fix show summary test.
Use okhttp 1.6.0.

- https://github.com/square/okhttp/blob/master/CHANGELOG.md#version-160.
Change log for v3.2.1.