Add snake gui app and update os/usr parts. Now snake can run!

user/src/bin/random_num.rs

@@ -0,0 +1,16 @@
+#![no_std]
+#![no_main]
+
+#[macro_use]
+extern crate user_lib;
+use oorandom;
+
+#[no_mangle]
+pub fn main() -> i32 {
+    println!("random num  program!");
+    let seed = 4;
+    let mut rng = oorandom::Rand32::new(seed);
+    println!("OORandom: Random number 32bit: {}", rng.rand_i32());
+    println!("OORandom: Random number range: {}", rng.rand_range(1..100));
+    0
+}