WebSearch: fix get_fieldvalues() when recid is str
WebSearch: fix get_fieldvalues() when recid is str

* recid might be string, so try to convert it to int in the get_fieldvalues
  function (needed for WebSubmit, major user of this function, which calls
  it in many different places with a string argument instead of int).

* Note: this was committed previously in
  705bb7160ce9691967b1504b28f230917c69149a
  but it was apparently dropped by mishap later.

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