Change version to 'latest-SNAPSHOT'

[tkrille]

This has to be done for the new release process to work. Otherwise we would have to increase the version somehow after release by Circle CI or worse: manually. There is no need to fetch a snapshot after a release, because the release contains the exact same code as the last snapshot. So having a universally working snapshot version, like 'latest-SNAPSHOT', should do no harm, but eases the burden of maintaining the right version between releases.

[tkrille]

I've updated the changelog.

[dacrome]

Thanks!