Simplify person serialization

Use the existing fields array to loop through and gather the relevant
bits of information that we want to persist back to the API.
Simplify person population

When the save is complete, loop through the existing fields array and
populate the person view page.
Allow mongoose to be put into debug model

By setting the MONGOOSE_DEBUG environment variable, mongoose will print
out all the database operations being performed.
Intercept person PUT requests and extract party

When a person is PUT to the API we extract the organization field from
the body and use it to associate the person with an organization which
represents their "primary" party.
Make sure organization fields get sent to the API

Without this the client side javascript doesn't process these fields
correctly.