Upgraded Ubunutu to 14.04

This commit:

upgrades:
  - the ubuntu image to 14.04 Trusty Thar
  in the base image:
    - phantomjs to 1.9.7
    - ruby to 2.1.6
    - gradle to 1.12
    - node to 0.10 (ignore patch versions because they don't break things)
fixes:
  - a bug which caused the java installation to fail #17, #20
changes:
  - the default user to root
  - the home directory to /root
  - all images to use the new user and home directory
  - some `wget` to `curl -O` (because it is quieter)
  - raw.github.com to raw.githubusercontent.com
  - the gcc images now get ffmpeg from ppa:jon-severinsson/ffmpeg because
    ffmpeg was removed from ubuntu's repositories