replace self closing script tag with open and closing tags

[justinledford]

The self closing script tag isn't recognized properly by some browsers. In the latest version of Chrome, all following tags are treated as children of the script tag.

This just replaces it with an open and closing tag.

[etimberg]

thanks @justinledford. You can see docs from master on http://www.chartjs.org/docs/master/getting-started/