Revert "Permanent redirect herokuapp.com -> heroku.com, fixes #59"

This reverts commit 63b4567bfe30e02573b6ae67d885bd1f5ef1ce59.

The client is not ready to follow this 301 just yet, see:
https://github.com/heroku/heroku/commit/5c89a16888668baa63eb7ffff8d07405f1fd6364