Enforce semantic dataset type definition when adding a new dataset

[navarroc]

Now that we have semantic type definitions, we can start minimally enforcing this when a dataset is added to the system. For example, if a user uploads a dataset as ergo:buildingInventoryVer7, we can minimally verify that the dataset has all the required fields in the type definition.

[ylyangtw]

This PR #263 adds minimal validation on definitions. It checks all the required fields before posting data.