Fixed BOM order for Drone

Fixed order for BOM. 

We need to work this better. Arquillian BOM contains a Drone BOM already, which is IMHO wrong. With current setup, we are order dependent for specifying Drone version.

We should either remove Drone from Arquillian BOM - rely on -with-tools BOM here, otherwise we would need to release a Arquillian BOM with every Drone final.

Same for selenium, we currently provide a default value, however we still recommend people to put Selenium BOM in there. We need to be more concise here.