sort sponsors on top - fixes #48

Now at the campaign pages the sponsors are ordered to the top of the list (issue #48). 

I had a problem with the 'this' keyword, which referred to the wrong context. I now changed it so that the functions are defined within the main sort function. That works, but is not optimal since they are defined every time the function is called. Maybe I rewrite it later, but that works for now.

- ju