Simple fund template

These commits unify all non-project details pages into a single url and adds a donation form on that page.

* Removed urls, templates, and views corresponding to for memorial, general, country funds
* Replaced with a single url, view, and template
* Abstracted donation amount form into an included template; used in both project and fund pages
* Removed second form from the project view
* Removed the "remaining amount" option from donations
* Removed tests for much of the above; added a test for donating to a fund