use ubuntu base image, export ports, use supervisord to run services (RStudio, ipython-notebook, ssh)
add locale, install necessary dependencies
update Dockerfile comments
update usage notes
fallback method if we cannot detect rstudio version, avoid chown issues
use file method instead to get latest version always
update documentation on Dockerfile and component files, showing how they are connected
Merge pull request #90 from cboettig/master

Updates dockerfile

Thanks Carl!