dbquery: more reinstall-friendly dbquery
dbquery: more reinstall-friendly dbquery

* Makes dbquery more reinstall-friendly by means of creating
  dbquery_config file that is not erased while `make install`
  process runs (which may be possibly lengthy).  It only changes
  by `inveniocfg --update` family of statements.

Reviewed-by: Tibor Simko <c7116e45300b163846dc01f3ed02116e3f8ef7a5@cern.ch>

inveniosoftware/invenio-accounts,inspirehep/invenio-accounts,tiborsimko/invenio-accounts,inveniosoftware/invenio-accounts,inveniosoftware/invenio-accounts,tiborsimko/invenio-accounts,inspirehep/invenio-accounts,inspirehep/invenio-accounts,tiborsimko/invenio-accounts