Replaced all occurrences of escape_string() in the search engine code.
Replaced all occurrences of escape_string() in the search engine code.

inveniosoftware/invenio-records,tiborsimko/invenio-records,inveniosoftware/invenio-search,tiborsimko/invenio-search,inveniosoftware/invenio-records,tiborsimko/invenio-search,tiborsimko/invenio-records,inveniosoftware/invenio-search