Data views: support filtering for metadata ID/SourceID

Filter syntax is like this:
id:<id1>[,<id2>,...]
source:<id1>[,<id2>,...]

This is a pragmatic solution to quickly allow filtering by metadata IDs.
A better solution would register the new filter types and adapt the filter
field to deal with all kinds of filters.

Change-Id: I72a8f17bceb89430cbc2d5514c4249110a28403b
Reviewed-on: http://gerrit.esdi-community.eu/3145
Tested-by: Jenkins <sitemple@igd.fraunhofer.de>
Reviewed-by: Simon Templer <simon.templer@igd.fraunhofer.de>