[Closes #43] API Client with Admin/Staff/Volunteer role can create a new Patient record

[samau3]

Closes #43.

This PR adds a new /register and /update route for patients.

• The /register route creates a new patient record with the bare minimum patient details necessary (e.g. name, DOB, etc.)
• The /update route allows a patient record to be updated for emergency contact, allergies, medications, medical conditions, hospital, and PCP
  • The update route returns the entire patient record
• The order in which allergies, medications, and conditions are sent in the request is preserved via join tables