Combine forms. Add requirement validation checking

* Combines the separate organization, individual, and dedication forms
* Adds validation checks to make sure conditionally required fields are met
* Adds JS to show/hide the organization/individual fields
* Runs all of the JS on page init. This is useful if the user has a validation error as the values on the form might not be their 'defaults' on page load in this case
It allows for the trailing slash to be present or absent. My understanding is that default django wants to insert those slashes, so we kind of wrestle with it when we don't allow the slash to be present (e.g. on eregs)