New getnodeaddresses call gives access via RPC to the peers known by
the node. It may be useful for bitcoin wallets to broadcast their
transactions over tor for improved privacy without using the
centralized DNS seeds. getnodeaddresses is very similar to the getaddr
p2p method.
Tests the new rpc call by feeding IP address to a test node via the p2p
protocol, then obtaining someone of those addresses with
getnodeaddresses and checking that they are a subset.
