Description of the issue

The OEMetabuilder and the table download functions return metadata in a different form.

Steps to Reproduce

1. Create a table through the upload wizard and look at the JSON there
2. download the table metadata in the table view

Ideas of solution

The two sources use different functions to return/create metadata. Either use the same function or if not feasible, adapt one function to match the output of the other.

Also see OpenEnergyPlatform/omi#99