Continuous deployment

@exalted It would be great if you could take a look at this as well. 
I ran the `travis setup heroku` command which indented the file as you see it. Now, I am pretty sure YAML syntax accepts both versions but since we might use the command in the future I decided to keep its version so that we won’t see any change later if we use it.

Also, I am pretty sure that the tool uses a YAML library internally which enforces some standard. I am ok with reverting it, too.