"Try in PWD" Button

[egeldenhuys]

We can deploy Docks to Play With Docker using a button, this would be great for demos.
[![Try in PWD](https://cdn.rawgit.com/play-with-docker/stacks/cff22438/assets/images/button.png)](http://play-with-docker.com?stack=https://<my_stack_url>)

However our current architecture does not support this. The address of the api has to be known at deploy time, but with PWD this is only known afterwards.

One solution would be to inspect the current URL in the UI. If it is something like http://ip172-18-0-11-bf12hss9cs9g00ffpc60-4200.direct.labs.play-with-docker.com then we set the API address as http://ip172-18-0-11-bf12hss9cs9g00ffpc60-8080.direct.labs.play-with-docker.com