First pass at user settings page
Stub controller for saving user settings
Adding routes for settings page
Adding settings page link to nav bar
Fixed "saving a model causes its props to be JSON serialized" bug.

This was documented in the group model tests and worked around in the
badge controller tests, and generally caused the behavior of models to
be highly unexpected.

This fix works by never mutating the model when preparing it for
the database.
remove api-easy as a dependency; use express cookie session instead of pkg.
initial conversion of issuer-test.js from api-easy to tap+request. messy.
'Page Not Found' template
'Not Found' middleware
Adding 'not found' middleware to app

This only seems to work by adding the `app.router` line, which seems to exist in other examples I've found, but not in our setup.
split out utility functions into test/app-utils.js.
more refactorings to test/app-utils.
even more refactorings to test/app-utils.
issuer.test.js now runs its own express server for hosting assertions.

this test now runs a LOT faster because it no longer needs to talk to
p2pu or github to find images and stuff.
generate hosted assertions for tests completely dynamically, enforcing DRY.
fixup auth mechanism for entire duration of app-utils.prepareApp().
Merge pull request #580 from andrewhayward/settings-page

Settings page
greatly simplified test/app-utils.js.

number of tests in test/issuer.test.js appears to be halved, but it's just
b/c we're not logging into the backpack for every single assertion we're
doing; instead, we login once and do a bunch of things while logged in.
refactored test/app-utils.js a bit more
added test/login.test.js.