Add donate banner to main Foundation site templates

[alanmoo]

Let's put the banner from the buyer's guide on the main foundation site template (except for campaign pages, and leave the Buyer's Guide as-is).

Let's start with item 7 for the copy from this doc

Longer term goal might include the ability to edit the banners in the CMS or A/B test them.

[kristinashu]

Might take some tweaking to get this longer copy to fit properly so I'll do a quick mockup.

[kristinashu]

Here are some comps https://redpen.io/p/awa941488658be2ec1

Not sure how set we are on #7 for copy but mocked up some shorter versions too. Seeing if Jesse has any feedback.

[alanmoo]

We might be able to use a different headline. Those items were all approved by legal and such, maybe @WillatMozFdn has something to add regarding the headlines and trying to keep them headline-length?

[kristinashu]

We're going to go with this one for now because the length is better (can always update the copy later if needed).