BibIndex: faster Solr full-text indexing
BibIndex: faster Solr full-text indexing

* Sends COMMIT instruction to Solr only at flushing frequency
  intervals, not after every record.  (closes #1167)

Co-authored-by: Patrick Glauner <5443b88bc6611431eef05c8ef00b7fee188ca13d@cern.ch>

tiborsimko/invenio,tiborsimko/invenio,inveniosoftware/invenio,inveniosoftware/invenio