Added mor features and fixed some bugs

Hi have added the request in pull request #14 to show the link description in the graph title and also added the ability to turn the graph description off to save space.
added various other fixes and improvements to make the system flow better and the graphs have more detail in them.
Added the feature to show the AS number and description in the graph titles. This can be enabled or disabled as required from the config.inc file.
I have also created an install script for CentOS user to make life easier and quicker when installing the system for the first time.
I have also made sure all pages now show the IPV6 information if this is enabled in the config.inc file as not all pages worked before.
Also added 2 more pages for the Top 20 AS information with more detailed information in them (Top AS - 4 Hour and Top AS - 12 Hour) this helps users when they first setup the system to see if data is being collected as the fine lines on the graphs are much thicker and easier to see.
Added the headermenu.inc file to allow users to change the links and description of the links on the pages from 1 place rather than having to edit each page individually.
Made sure the View and AS-SET page now shows the IPV6 information for an AS-SET or AS Number if the Show IPV6 option is st in the config.inc file.