Patch 4

This patch will make haxe-users be able to embed the try-haxe code on their website/blog.
It will look like this:
![try-haxe-embed](https://cloud.githubusercontent.com/assets/576184/5151306/6821266c-71dc-11e4-80af-dfa3ac6ba6f8.PNG)
Features: view,run source and an option to edit it using a link back to try-haxe.

I will provide a nice wiki-page for users to know how to embed it when it's up and running.

At the moment it works with _/app/embed/UID_. In ideal cases it will be _/embed/UID_, as discussed.
I hope you can find time to move the /app/ to the root folder. I tried to make that work, without success.