A Better Way to Upgrade to Trusty (pjz + mpeterson)

Nothing innovative in this pull request. I applied mpeterson's patch to 'just use sed' instead of keeping a copy of it because this is simple and elegant. All I did then was to bump the base FROM ubuntu:14.04 in the Dockerfile. 

Hopefully this gives you a pull request that saves you 5 minutes. Cheers and thanks for all the work you've done.