Get and verify the latest tag, import the key for another Ubuntu dev

Updated the guide to import the key for yet another Ubuntu developer, get the latest tag in the Ubuntu Trusty repository and verify it.
Do we need to double-check the fingerprint, or are we assuming the user is using a recent enough gpg that has had that [issue](http://bugs.gnupg.org/gnupg/issue1579) patched? I dug around for a minute but couldn't easily find which version of GPG fixed that problem.