Remove unhelpful try-except wrapping
Remove unhelpful try-except wrapping

These just hid the original error, complicating troubleshooting. If user
needs to be spared the error details, then that should happen higher up.

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