Fixed download page / Updated index.html / Added heca monster image

This pull includes:
(1) 
fix of the download page - the existing download table rows are split after column 5 - this issue has been corrected; additionally I have reformatted the table using the www.kernel.org example.

(2)
The index.html has been improved adding an Introduciton section which explain about the tools/capabilities/license. The other sections were improved, including correction of a broken link.