Blueprint visualizes triples from local file

[magdasalatka]

Users working on visualizing layer may spot missing data. However, they often won't have write access to the store. We need to provide them a way to manually add new triples. These triples will be pooled together with data coming from the store, and visualized together in Blueprint.

Source: feedback from Jean-Luc

TODO:

• Add UI interface to upload triples
• Collect metadata about this manual upload: timestamp, user, description
• Store these triples (user uploaded + metadata) in local.ttl files
• Merge dataset coming from local store together with datasets coming from local .ttl files
• Adjust visualization to show all relevant data from merged dataset