Update README.md and sample.config.ini

README.md
    * Now contains a sub-command description for treecompose,
      imagefactory, and installer

sample.config.ini
    * Heavily commented the sample file as well as added the new
      options (docker_os_name and configdir) that has been added
      recently.
Merge pull request #31 from baude/readme

Update README.md and sample.config.ini