Send fewer spam messages in p2p_invalid_messages
Send fewer spam messages in p2p_invalid_messages

Builds on travis are failing because the test node isn't
able to drop all the bad messages sent within the given
timeout. Reduce the number of bad messages we're sending
and increase the timeout to avoid failures on travis.

chaincoin/chaincoin,chaincoin/chaincoin,chaincoin/chaincoin,chaincoin/chaincoin,chaincoin/chaincoin,chaincoin/chaincoin