Add pages financial disclosure info, new donation video

Creates two new pages

* Financial disclosure info/FAQ page that lists links to our relevant financial documentation — [jekkit preview](http://jekit.codeforamerica.org/codeforamerica/codeforamerica.org/financial-info-updates/support-us/)
* Donation video page that includes a new embedded video with info about our campaign and analytics-tracked donate button — [jekkit preview](http://jekit.codeforamerica.org/codeforamerica/codeforamerica.org/financial-info-updates/support-us/help-build-it)

Note: Some in-page styling on /support-us/help-build-it because .layout-semibreve has some extra padding-top that .layout-breve doesn't. TODO: Investigate this in pattern portfolio.

//cc @Jaime-Alexis Please give me a :+1: here and I'll merge.