use newest berkshelf
change defaults to nexus 2.3
clean up credential code
use newest yum cookbook because of missing epel packages error
nicer way to ensure nexus is available before running lwrps
set an attribute after the admin credentials change
include build-essential
use metadata as version source for berkshelf
Merge pull request #20 from RiotGames/nexus_2.3

Support Nexus 2.3