Merge pull request #5424 from abhgupta/abhgupta_nextgennode

Rebase next_gen_node on master
rework broker builder to use external assemble/run scripts
Merge pull request #5416 from bparees/remote_scripts

Switch broker builder to use external assemble/run script location
Fix the sources path for broker-builder
Merge pull request #5436 from mfojtik/fix_broker_build

Fix broker-builder assemble script and Dockerfile to make it run with ruby-19-centos image