Upgrade Docker to 0.11 RC

* Default to installing from the Docker repository instead of Canonical repo
* Add ability to install from Docker repository, as Canonical repo lags
* Giver Docker non-root access
* Add docker alias when installed via docker.io package with update-alternatives
Adding box sizes to README.md
Adding build status badge
Adding Cloudbees props
Update Acknowledgements
Update README.md
Update README.md
Update README.md
Update README.md
Update README.md
Only install vagrant-serverspec if not already installed
Adding Makefile for caroline build machine
Adding Makefile for winry build machine
Adding ssh-* targets for convenient testing
Do not remove Linux headers during minimize step

Removing Linux headers seems to be causing issues around guest tool
builds in recent updates to Ubuntu 14.04. Leaving the headers around
seems to address any issues and they don't make the compressed image
much bigger.
Pushed v1.0.2 build to VagrantCloud under https://vagrantcloud.com/box-cutter
Make headless a command line parameter and Makefile option (HEADLESS)
Values can be "true" or "false".  Default is false.
Adding "make validate" target which runs "packer validate" on all templates.
Add option to peform kernel upgrade - AUTO_UPGRADE="true" (default is "false")
Removing extra apt-get call.