Create a new Funders page that attributes the many different funders (current and past) of the Kit

[colinbdclark]

At the moment, the only funding attribution on the site is the Hewlett Foundation. However, a number of other funders, including CIFAR through the Data Communities for Inclusion project, have contributed to supporting the site. We should create a page that reflects the diverse sources of funding, and updates the footer to point to it.