Add and call test_paging function

src/lib.rs

@@ -59,13 +59,7 @@ pub extern fn rust_main(multiboot_information_address: usize) {
     let mut frame_allocator = memory::AreaFrameAllocator::new(kernel_start as usize,
         kernel_end as usize, multiboot_start, multiboot_end, memory_map_tag.memory_areas());
 
-    for i in 0.. {
-        use memory::FrameAllocator;
-        if let None = frame_allocator.allocate_frame() {
-            println!("allocated {} frames", i);
-            break;
-        }
-    }
+    memory::test_paging(&mut frame_allocator);
 
     loop{}
 }