[COOK-3833] Enable mirror repository for package installation type [COOK-3969] runit services for Jenkins and Nodes do not source global environments. Impacts external groovy scripts

[COOK-3833]
This change adds the attribute pkg_mirror (defaults to
pkg.jenkins-ci.org).
Local repositories are usable and the server-package receipt is compareable to the war-file installation.
[COOK-3969]
Without sourcing the /etc/profile several Jenkins tasks with external groovy can´t work because the Jenkins and slave process do not include changes within /etc/profile.d/ provided from cookbooks like ark.
A fix is provided in github that includes /etc/profile to make environment variables available for external script interpretors like groovy.
Jenkins Server installation made with type "package" are not affected.