Bump version to 0.2.0
Bump version to 0.2.0

This uses datapackage-registry 0.3.0, which in turn uses the updated schemas
that have relative $refs to DRY them up.

datapackages/datapackage-py,sirex/datapackage-py,sirex/datapackage-py,okfn/datapackage-py,okfn/datapackage-py,okfn/datapackage-model-py,okfn/datapackage-model-py,datapackages/datapackage-py