Do not deploy with pull requests

Now every build wants to deploy to gh-pages, even pull-requests. PRs
will of course fail, but this adds at on minute extra time for the Luna
build which is totally unnecarry. From now on, PR builds does not even
try to deploy.
Merge pull request #290 from WonderCsabo/doNotDeployWithPullRequests

Reduce build times for pull requests.