CentOS/RHEL 6 have gcc 4.4.7 by default, which does not support -std=gnu++11.
Previously, packages like digest were failing to compile on CentOS 6 using the
default gcc.
* Allows building of RPMs for CentOS 6
Builds on earlier work and provides the tooling required to create Linux OS packages (deb in this case).
Modifies: Dockerfile.centos-6
So that it includes the fpm package build tool and also copies in the packaging script
Adds: package.centos-6
which is the packaging script which runs fpm with the required parameters and dependencies
* Added additional font dependency
