[#60] Enable builds on AppVeyor
[#60] Enable builds on AppVeyor

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