Create a CKAN extension for the taxonomy usage

[TBoonX]

Requirements from the proposal:

• automatic completion and recommendation of tags for datasets based on local or remote taxonomy graphs
• Creation of taxonomy content and transfer it to a SPARQL endpoint
• mass editing of tag recommendations of local datasets based on retrieved taxonomies

[TBoonX]

Atm the extension adds a field "semantic tags" to a dataset. The tags are read from the SPARQL endpoint and could be saved.
Issues:

• normal tags are overwritten
• new semantic tags could not be added via the dropdown

[TBoonX]

Basic functionality is working. This task is fulfilled.