Add NODE_BLOOM service bit and bump protocol version

Lets nodes advertise that they offer bloom filter support explicitly.
The protocol version bump allows SPV nodes to assume that NODE_BLOOM is
set if NODE_NETWORK is set for pre-70002 nodes.

Also adds an undocumented option to turn bloom filter support off for
testing purposes. Nodes attempting to use bloom filters are immediately
dropped so as to not waste their bandwidth.
Merge branch 'node-bloom-service-bit' of github.com:petertodd/bitcoin
additional Dogecoin 1.6 changes