Fixed two problems:

1. The install script for python2.7-dev incorrectly forgets the link

       ln -s /usr/bin/python2.7-config /usr/bin/python-config

   this is now added.

2. Our python code also has dependencies that were not satisfied as
   a result of simply adding the R packages that depend upon so1utils,
   so1recom, and so1engine. They are the following and were added

   a. numpy - Installed on the image as a result of this commit
   b. pandas - Installed on the image as a result of this commit
Added a slightly better description of the image