refactor(build): simplify and modularize

simplify:
- use same html file for dart and JS
- build benchmarks automatically when doing `gulp build`
- centralize configuration

modularize:
- move all build tasks into separate node.js modules under
  `tools/build`.

changes:
- the `build` folder is now the `dist` folder

Closes #284

modules/facade/bootstrap.es5

@@ -1,12 +0,0 @@
-/**
- * This is a special facade used to bootstrap JS automatically. 
- * (In contrast to door wheere the user needs to explicitly call into angular.)
- * This file is appened to AngularJS and needs to be written in ES5.
- */
-(function(window, document) {
-  document.addEventListener('DOMContentLoaded', bootstrap, false);
-  function bootstrap() {
-    // TODO(misko): load application factory from the module system.
-    applicationFactory().run();  
-  }
-})(window, document);