Updates introduce usage of client-side aspect dropdown rendering

Remove pagination from json format of contacts#index; add explanatory comments. I KNOW. But it's super confusing and I can't find a way to rewrite the code to be more clear. Soloing FTL.

Refactor contacts#index to have explicit html and mobile formats again, because apparently infinite scroll wants the html version, not the json version.

Refactor contacts#index specs. json requests now paginate correctly, but infinite scroll is still broken.

Put a select limit on the person query on contactsController index, since we know exactly what we're doing with the data

made aspect_dropdown ajax in (created route), in the process of removing aspect_membership js responses