Inital work on Rust support (#333)

* Inital work on Rust support

* update accepted runtimes

* fn: fix rust build

* Last tweaks and README.md

* fix typo

* update comment on rust.go

examples/hello/rust/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "func"
+version = "0.1.0"
+authors = ["Seif Lotfy <seif@iron.io>"]
+
+[dependencies]

examples/hello/rust/README.md

@@ -0,0 +1,30 @@
+# Using rust with functions
+
+The easiest way to create a iron function in rust is via ***cargo*** and ***fn***.
+
+## Prerequisites
+First create an epty rust project as follows:
+```bash
+cargo init --name func --bin
+```
+
+Make sure the project name is ***func*** and is of type ***bin***. Now just edit your code, once done you can create an iron function.
+
+## Creating an IronFunction
+Simply run
+
+```bash
+fn init --runtime=rust <username>/<funcname>
+```
+
+This will create the ```func.yaml``` file required by functions, which can be built by running:
+
+```bash
+fn build
+```
+
+## Testing
+
+```bash
+fn run
+```

examples/hello/rust/src/main.rs

@@ -0,0 +1,10 @@
+use std::io;
+use std::io::Read;
+
+fn main() {
+    let mut buffer = String::new();
+    let stdin = io::stdin();
+    if stdin.lock().read_to_string(&mut buffer).is_ok() {
+        println!("Hello {}", buffer.trim());
+    }
+}