WebSearch: improve detection of record owners

• If CFG_CERN_SITE, consider the possibility of the owner of a record being an egroup, defined as 'foo@cern.ch' insted of 'foo [CERN]'. (addresses #2068)

Signed-off-by: Ludmila Marian <ludmila.marian@gmail.com>
Reviewed-by: Tibor Simko <tibor.simko@cern.ch>