p2p: fix call to Server.removePeer

The gui already waits and shuts down ethereum. There was no need to wait
for an additional shutdown.

p2p: fix decoding of disconnect reason

Test-tastic.

- new flag nat for nat support UPNP|PMP
- new flag pmp for PMP gateway IP
- add NatType to utils/cmd to get p2p.NAT from nat type string
- obsolete usepnp flag
- get rid of IsUpToDate and sleep in miner start
- ethereum constructor takes nat type, port, maxpeer
- add pubkey arg to client identity

- add Status() to return td, currentblock hash, genesis hash
- GetChainHashesFromHash -> GetBlockHashesFromHash

- new interface explicit backend components txPool, chainManager, blockPool
- added protoErrorDisconnect for blockpool callback (FIXME: handling peer disconnects)

- changed backend interface
- using callbacks for blockPool
- use rlp stream for lazy decoding
- use peer as logger
- add id (peer pubkey) to ethProtocol fields
- add testPeer to protocol test (temporary)