use a donate form with a configurable paypal id

readd paypal button id

fixed a link titled 'RSS' linking to an atom feed

Fix one spec on FF; pendingify the other until I can figure out what's going on. Seems to be different behavior of the expander plugin across chrome and FF.

Clicking 'read more' now removes the link and collapses the adjacent paragraphs. Also: hella semicolons. Fixes #2766

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.