initial checkin
Original contents merges changes from https://github.com/dockerfile/nginx and dockerfile/ubuntu.
Created a copy of nginx.conf in repo, so changes can be easily made outside of the */conf.d/ and */sites-enabled/ directories.
Exposed volume for site files in /var/www. Not in original source.
changed dependencies to ubuntu:12.10 from dockerfile/ubuntu. updated installation to use only docker build instructions from new git repo. updated usage to describe use of new exposed VOLUMES in dockerfile.