respect documentId and/or collectionId in follow-up search

The search plugin supports limiting the search in current document and/or
collection. This setting get's lost after the search results are listet.
A follow-up search will search in all available documents and
collections.

This fix gets the document or collection UID from the available facet
search metadata.
cleanup debug output
Merge pull request #20 from stweil/fixes

Two small code fixes
Merge pull request #19 from albig/fix-search-in-collection-and-document

Fix search in collection and document
Debug output for import

Signed-off-by: Stefan Weil <sw@weilnetz.de>