Prescale instances before deployment

[FinnIckler]

Makes sure we have an instance available to deploy. Should reduce deployment time by another couple of minutes. I moved the staging deployment around a bit (uploading to S3 early) so we can be sure the deployment finishes in the 5 minutes after starting the server (otherwise the instance will automatically scale down because it's not used). I checked and it takes about 1-2 minutes to build and push the last image, so this should be fine.