Remove support for ISLookup-based concept import mode

[marekhorst]

This is #1434 follow up.

It was planned to support both concept importing modes by IIS for the time being:

• ISLookup based
• Context Streaming endpoint based

until both BETA and PROD environments are switched to the newly introduced Context Streaming endpoint.

Once ISLookup-based concept import can be dismissed we should drop support for this mode in IIS by:

• removing execution path declared in an oozie workflow
• removing classses (including ConceptXmlHandler, there is also ObjectStoreFacade which does not seem to be used anymore)
• removing unit and integration tests