add instructions for using docker with puppet
Merge pull request #631 from garethr/puppet_usage_docs

+ Documentation: Added a section on how to use Docker with puppet.
Add information about kernel requirements

This page will be helpful for people who:
- want run run a custom kernel
- want to enable memory/swap accounting on Debian/Ubuntu
Add some details about pre-3.8 kernels
Added a "we are hiring" to the frontpage of the docker website, and fixed two broken links in the docs.
Merge pull request #632 from jpetazzo/626-kernel-docs

+ Documentation: Added a section for Kernel requirements to the Docker Docs.