WebSearch: space between records in MARC HTML

* Sets a local margin ("1em 0px") for the HTML pre element when displaying
  records using the "hm" (MARC HTML) output format, so that records are
  split by a small space.

Signed-off-by: Nikolaos Kasioumis <nikolaos.kasioumis@cern.ch>
Reviewed-by: Tibor Simko <tibor.simko@cern.ch>