Merge branch 'release-0.3.0' into dev
Start next dev cycle.
Use secure endpoints.
Use `setEndpoint` instead of deprecated `setServer`.

- See https://github.com/square/retrofit/blob/master/CHANGELOG.md.
Change log for 0.4.0.
Update okhttp version recommendation.
Make this 0.4.0.
Merge branch 'release-0.4.0'