database: recommondations on database indexes

The web-interface will get slower and slower as more records are added.
As I don't know enough about database, I have to rely on advice from others.

These indexes were recommended by a user of the IPTV-analyzer:
 create index idx_logevent_rtime on log_event(probe_id,record_time);
 create index idx_logevent_mchannel on log_event(multicast_dst,record_time);

Which solved his performance issues.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>