[PD-517] Activity filter

This pull request implements sorting and filtering by contact record dates. I'd really appreciate feedback on this as there's what I am sure is a lot of unidiomatic Javascript within. 

Given that most of this was implemented in stylesheets and templates, there wasn't much to test. I plan to address that in a separate pull request, which includes my work with selenium as well as factory boy refactoring (that branch has existed for a while now publicly).