RPC & Client (#21)

* Initial version of http server.

* Refactor the structure.

* add unassigned ports info.

* Rename servers to match conventions.

* Add client crate and some proper RPC implementations.

* Style & docs.

substrate/rpc/src/chain/error.rs

@@ -0,0 +1,40 @@
+// Copyright 2017 Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+use rpc;
+
+error_chain! {
+	errors {
+		/// Not implemented yet
+		Unimplemented {
+			description("not yet implemented"),
+			display("Method Not Implemented"),
+		}
+	}
+}
+
+impl From<Error> for rpc::Error {
+	fn from(e: Error) -> Self {
+		match e {
+			Error(ErrorKind::Unimplemented, _) => rpc::Error {
+				code: rpc::ErrorCode::ServerError(-1),
+				message: "Not implemented yet".into(),
+				data: None,
+			},
+			_ => rpc::Error::internal_error(),
+		}
+	}
+}