Update to omnibus v4
Use new image
Merge branch 'master' into omnibus4
Command name change
Fix permissions on prerm
Lock to my version of omnibus
Try signing packages
Revert "Try signing packages"

This reverts commit f61d0c561ebdbfb13e8b521d6e1aea5024bbd4f1.
Json is required for omnibus - this fails on centos
Prepare for merge to master
Merge pull request #54 from flapjack/omnibus4

Switch to Omnibus4