Fixes AMD loading

If you're proxying an app that uses RequireJS and you include the `<script>` tags at the bottom of the `<body>`, the inner app will assume that the modules are being included for it.

This PR instead attaches the `<script>` tags as the first children of the `<body>`, so that browser-sync can start up and its modules won't be in conflict with the inner app's.

Fixes #2 with all tests passing.