TDS-4 Add login support

Have started adding login support, in terms of creating a simple framework by which normal page operations can be intercepted based on a login status.
TDS-9 Introduce a cleaner separation between person/user and patient

APIs, including URLs, now use the person ID rather than the patient ID.

Handling of requests for patients with non-patient IDs are not yet handled cleanly.
TDS-9  Introduce a cleaner separation between person/user and patient

Now working with separate person/patient tables, and have separate person/patient pages, although these aren't final, the patient pages still represent the structure of the original 'user' pages.  Haven't implemented any pages yet for admins nor doctors.