Consider increasing resources for CI

Currently our CI runs on two servers in the same datacenter. If one of them breaks, or something breaks in the DC, this could impact our ability to release in time. We should consider adding more resources, so that one server can always fail without impacting our ability to release in a timely manner.

Preferably, an extra server would be deployed in a different datacenter. We should investigate how well a Jenkins worker performs with its master not in the same network.