Close and tag milestone v0.3

[kengu]

Hi

I'm just about ready to make the first official release. Snapshots are now deployed to Sonatype snapshot repository on every push to origin (working on limiting deployment to origin/master only, but Travis contains a bug preventing this). Next step is to stage and promote Maven artifacts for release.

Do you (@leiva and @igieon) have any thing in the pipeline that you want to include in this release?

I plan to complete milestone v0.3 within a week or so.