renamed start script to redmine
Dockerfile: copy resources in a single ADD command
install: setup log rotation for redmine and supervisord logs.
install: make tarball extraction verbose.
redmine: redmine script can now be passed commands to perform specific tasks.

eg.
docker run -i -t sameersbn/redmine help
redmine: added migrate command to perform database migrations
redmine: added bash command to start interactive bash shell
redmine: upgrade to redmine version 2.4.1
README: add docker pull sameersbn/redmine as the preferred method of installation.
README: added redmine version information
README: updated instructions to use the initialize command.
README: added upgrading section.