Add initial migration and participant adding/editing

This adds participant adding and editing, in the "Manage Participants" section. Also includes the initial db migration.
I made a compromise here that I need to figure out. I'm using this template to only display the errors for this form. The thing is that the wireframes put the "Edit Participant" form in a modal dialog -- and I wanted to keep things as simple as possible by not using django-rest-framework and AJAX interaction for this form.

I think I need to make a choice here:
- If I'm using the modal dialogs, I need to add AJAX functionality using djangorestframework.
- Otherwise, the "Add Participant" button will bring the user to this template, which will have a `{{form}}`.

Do you have any suggestions? Do you think it's worth it to use modal dialogs and AJAX calls? Personally, I prefer not to use JavaScript when it's not necessary.