Create a NEXT release

I'm thinking about releasing v0.2 so that the Saturn team can use the conformance tests,
see @lidel comment in https://github.com/ipfs/gateway-conformance/issues/80

Ideally, we'd have a "next" version that we release on every merge to master. Teams that start setting up the test suite and needs the latest changes to do so would use that branch as a temporary target. This opens up the opportunity to make small adjustments before cutting a release.

cc @galargh