Add demo in command profile on how to launch the new importer

On TVB docs site, under "demos" and in category "Interacting with the Framework" we should have a new script which:

• shows how an import of a Connectivity from ZIP file happens
• show how an import from a BIDS folder with a structural connectivity happens

This demo will work only with tvb web gui installed (launched at least once and setup) on the local machine. This should be explained at the begining.