Scrollable Checklists for filters

[makermelissa]

The manufacturers list is starting to get a bit long on the filters page. Having a scrollable checklist would make it a bit more manageable. Additionally, if we wanted to be able to have modules as an option, this would allow it to exist without taking up a ton more room. It should be fairly easy to implement by placing the checkboxes inside a scrollable div with a maximum height.