Add container tagging, info, update script, govendor/vendorcheck support

This adds

• An update script build_update.sh, replacing the git subtree merge technique. You can download it via that link and run it to update to current. It's included in this release so won't have to be downloaded after that.
• Automatic addition of commit and build information to docker containers. Quick 2:45 screencast
• Adds vendorcheck/govendor support as described in README.md

Initial deployed release

This release is in use on most drud repositories already, and has been stable for a week or two. It has one major problem - the instructions specify an install and upgrade technique using git subtree which is not sustainable - it doesn't work with either PR squashing or rebasing in development.