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/rpcclient.h

@@ -0,0 +1,17 @@
+// Copyright (c) 2010 Satoshi Nakamoto
+// Copyright (c) 2009-2013 The Bitcoin developers
+// Distributed under the MIT/X11 software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef _BITCOINRPC_CLIENT_H_
+#define _BITCOINRPC_CLIENT_H_ 1
+
+#include "json/json_spirit_reader_template.h"
+#include "json/json_spirit_utils.h"
+#include "json/json_spirit_writer_template.h"
+
+int CommandLineRPC(int argc, char *argv[]);
+
+json_spirit::Array RPCConvertValues(const std::string &strMethod, const std::vector<std::string> &strParams);
+
+#endif