Install embedded chef 11.4.0.rc.0 via Rubygems in `chef-server` project

This version of Chef fixes the dependency hell caused by the net-ssh and 
JSON gems. It also moves us to a place where the embedded Chef is 
installed via Rubygems (vs pulled down from Git).
Add proper escaping to backslashes in `chef-server-ctl` bash script
Merge branch 'embedded-chef-via-gem'