Fix jshint warnings
Add master method to popit class

This enables easy access to the master connection rather than having to
store a separate one for accessing accounts.
Add configurable cookie domain to session middleware

Allow the cookie domain for the session middleware to be configured and
default it to the new setting.
Move registration app out of the main auth app

This allows us to use the registration part of the auth app in the
hosting app rather than in the instance app. This is preferable because
people will want to register for an account before creating an instance.
Add supertest dependency
Split up the app from the server

By separating these two modules we can test the application in isolation
using supertest without having to worry about the server starting up and
binding to a port.
Move sessions and auth into the master app

Rather than handling these separately in the hosting and instance apps
it's more straightforward to just handle these in the top level
application. By doing this we can reuse the same logic to keep the user
logged in across instance and hosting apps.

I've also switched the sessions to use signed cookies rather than mongo
which is much simpler and removes problems with hanging connections when
testing.
Tests for the registration process

These are some basic tests for the popit registration process. They're
full integration tests, so hopefully they can be a basis for future
tests are of sort.
Add user information in the head of hosting app

This information isn't actually shown to the user (it's commented out)
but it is used in the tests to assert that the user is logged in (or
not).
Don't delete css before running tests