Make contributor bar more efficient

I've rewritten most of the contributor bar stuff.  Here's how I've made it more efficient:

1.  Using event delegation instead of assignment to each individual link.
2.  I'm never querying for elements before I need them, thanks to adding a classname for both shown and hidden elements, as well as using a data-attribute to track that.
3.  Un-nesting CSS for this block.

Let me know if you have questions.
this needs to be `{% trans count=contrib_count %}` to work properly and the inline variable needs to stay `{{ count }}`