testsuite: update path to XML event config base dir

Related to #668

Signed-off-by: Jakub Filak <jfilak@redhat.com>
testsuite: do not require core_backtrace in koops problems

satyr do need this file, the file was required by btparser

related to abrt/satyr#88

Signed-off-by: Jakub Filak <jfilak@redhat.com>