add-site-to-new-patient

[eatyourpeas]

Overview

Fixes the issue but actually identifed some other bugs.

1. on new patient form - fixes validation error from selects where value not passed back to form class from template
2. adds site to valid new patient before save
3. returns patient cohort from auditcohort model str method
4. removes delete method from patient model
5. fixes patient filter in patient list to include only active cohorts

closes #115