Split up bitcoinrpc (code movement only)

Split bitcoinrpc up into

- rpcserver: bitcoind RPC server
- rpcclient: bitcoin-cli RPC client
- rpcprotocol: shared common HTTP/JSON-RPC protocol code

One step towards making bitcoin-cli independent from the rest
of the code, and thus a smaller executable that doesn't have to
be linked against leveldb.

This commit only does code movement, there are no functional changes.

src/rpcdump.cpp

@@ -2,10 +2,8 @@
 // Distributed under the MIT/X11 software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-
-
 #include "base58.h"
-#include "bitcoinrpc.h"
+#include "rpcserver.h"
 #include "init.h"
 #include "main.h"
 #include "sync.h"