fix(helm_chart_verify): coerce gpg into using old keyring format
fix(helm_chart_verify): coerce gpg into using old keyring format

This avoids the Error: failed to load keyring: open /home/jenkins/.gnupg/pubring.gpg: no such file or directory
See https://www.gnupg.org/faq/whats-new-in-2.1.html for an explanation of why the presence of pubring.gpg
changes GPG's behavior to be more compatible with helm.

deis/jenkins-jobs