Change references to linkeddata.github.com

[kirkhess]

In https://github.com/linkeddata/tabulator/blob/master/js/mashup/mashlib.js

The scriptBase statement refers to a non-existent url & the iconPrefix needs to be fixed as well.

tabulator.scriptBase = 'https://linkeddata.github.com/tabulator/'; // This no longer works.

tabulator.iconPrefix = tabulator.scriptBase; //this also needs to be fixed

See linkeddata/tabulator-chrome#4