plugins: add abrt-action-generate-machine-id

Enabled by default on RHEL7.

Resolves: rhbz#1140044

Signed-off-by: Jakub Filak <jfilak@redhat.com>
spec: add abrt-action-generate-machine-id

Related to rhbz#1140044

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