allow autotest frontend to run from non standard browsers (like IE)

some browsers (notably IE up to version 8) don't support
standard addEventLister so we need to adjust the way event
for spreadsheet is wired in job detail view page

Signed-off-by: Julius Gawlas <julius.gawlas@hp.com>
server/autotest_remote_unittest.py: Fix unittest

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>