Travis setup 3

Third time's a charm

I've tested this as far as I can without it running on the skulpt account. If everything is as it looks this will:

* compare tags
* push the build to the dist repository and tag it with the same tag as the one from skulpt
* it will also push the HEAD version to the dist repository
* and it will update the site with the build of the latest tag called skulpt-latest.tar.gz and skulpt-latest.zip

Oh yeah what is doesn't do (correctly):

When tags aren't created in the correct order so `0.9.1` after `0.9.2` the tags in the dist repository will be in the wrong order. 

There are 4 secure vars and I think that is one to many we'll have to see what happens when this PR is pulled.