rpm: Add "role" package attribute

For now, the only meaningful role is "affected", meaning that the
package contains the executable/script that crashed. In the future, we
can add other roles as needed (offender, related, interpreter, runtime
environment, ...).

Fixes #84.

Signed-off-by: Martin Milata <mmilata@redhat.com>
Signed-off-by: Richard Marko <rmarko@redhat.com>
abrt: Don't fail if there's no dso_list

This behaviour prevented satyr from generating uReports for e.g. python
crashes.

Signed-off-by: Martin Milata <mmilata@redhat.com>
Signed-off-by: Richard Marko <rmarko@redhat.com>