Get most of yew in place

Doesn't actually run though...

percy/src/lib.rs

@@ -0,0 +1,20 @@
+#[macro_use]
+extern crate virtual_dom_rs;
+
+extern crate percy_webapis;
+extern crate wasm_bindgen;
+
+use percy_webapis::log;
+use percy_webapis::Element;
+use wasm_bindgen::prelude::*;
+
+#[wasm_bindgen]
+pub fn main() -> Element {
+    log("Entered Rust code");
+
+    let elem = html! {
+        <span> {"It is alive!"} </span>
+    };
+
+    elem.create_element()
+}