Add memory information

kernel/scheme/sys/memory.rs

@@ -0,0 +1,10 @@
+use collections::Vec;
+
+use arch::memory::{free_frames, used_frames};
+use syscall::error::Result;
+
+pub fn resource() -> Result<Vec<u8>> {
+    let string = format!("Memory Used: {} KB\nMemory Free: {} KB\n", used_frames() * 4, free_frames() * 4);
+
+    Ok(string.into_bytes())
+}