Rust JSONRPC Client

Rudimentary support for sending JSONRPC 2.0 requests and receiving responses.

To send a request which should retrieve the above structure, consider the following example code

```rust extern crate jsonrpc; extern crate serde;

[macrouse] extern crate serdederive;

[derive(Deserialize)]

struct MyStruct { elem1: bool, elem2: String, elem3: Vec }

fn main() { // The two Nones are for user/pass for authentication let mut client = jsonrpc::client::Client::new("example.org".toowned(), None, None); let request = client.buildrequest("getmystruct".toowned(), vec![]); match client.sendrequest(&request).andthen(|res| res.intoresult::()) { Ok(mystruct) => // Ok! Err(e) => // Not so much. } }

```