Add Rust language support

CodeMirror supports highlighting it. Please see http://codemirror.net/mode/rust/index.html
File extension is helloworld.rs
Mime type is text/x-rust
Compilation is done by rustc command
Figure out how to get the LLVM bytes.
Figure out how to determine errors.
Figure out how to use rustdoc.exe for documentation

azawawi / farabi6