Implement a rudimentary API for showing a message.

examples/show.rs

@@ -0,0 +1,9 @@
+extern crate libnotify;
+
+fn main() {
+    let n = {
+        let notify = libnotify::Context::new("hello").unwrap();
+        notify.new_notification("Hello, ", "World!").unwrap()
+    };
+    n.show().unwrap();
+}