Remove redundant '/' from JS url.

[MineForeman]

The generate url for the javascript reads;-

/plugins/digg-digg//js/diggdigg-floating-bar.js

It should read;-

/plugins/digg-digg/js/diggdigg-floating-bar.js

This can cause issues when generating static copies of the website with plugins like simply-static, this change removes the redundant '/' .