Update test components to not reference window

Author: Nick Maher

test/dummy/app/assets/javascripts/components/Todo.js.jsx.coffee

@@ -4,4 +4,4 @@ Todo = React.createClass
 
 # Because Coffee files are in an anonymous function,
 # expose it for server rendering tests
-window.Todo = Todo
+this.Todo = Todo

test/dummy/app/assets/javascripts/example2.js.jsx.coffee

@@ -2,4 +2,4 @@ Component = React.createClass
   render: ->
     `<ExampleComponent videos={this.props.videos} />`
 
-window.Component = Component
+this.Component = Component

test/react/jsx_test.rb

@@ -15,7 +15,7 @@
     }
   });
 
-  window.Component = Component;
+  this.Component = Component;
 }).call(this);
 eos