Simplify config for testing w/ local HOSTS file

This setup assumes that we will test logins, etc. locally, using a
modified HOSTS file to spoof the final tree.opentreeoflife.org domain
for login and authentication. See TODO's for items that would need to
change before final deployment.

Why test using ot15 and other machine-specific domains? Because the
servers also call each other, without the benefit of a modified HOSTS
file. This will introduce calls to the *real* tree. and api. servers,
which could mask (or create) errors in the system under test.