BibFormat: fix for XSS vulnerability in `ln`
BibFormat: fix for XSS vulnerability in `ln`

* Fixes XSS vulnerability in language parameter for queries such as
  </search?ln=en296b9%22%3E%3Cscript%3Ealert%281%29%3C/script%3Ee2d>.

Reported-by: Pietari Hyvärinen <0499b47116ac16c71981d7f054c9a6391c4ecd8f@csc.fi>
Signed-off-by: Tibor Simko <c7116e45300b163846dc01f3ed02116e3f8ef7a5@cern.ch>

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