WebSearch: workaround for fulltext phrase search
WebSearch: workaround for fulltext phrase search

* Currently, the phrase index is disabled for the fulltext index.
  Until it is enabled, let us search for word combination instead
  of for phrase, so that users may see some relevant results instead
  of just no results.  Phrases may be seen in the snippets.
  (addresses #272)

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