https://jira.ez.no/browse/EZP-29143 and https://jira.ez.no/browse/EZEE-2304 adopted current tests for demo versions, but no nighly builds taking advantage of this takes were added.

This story should:
1) add nightly builds and Slack notifications to ezplatform-demo and ezplatform-ee-demo
2) make sure that everything that was done in the tasks mentioned above is run on Travis