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.
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().
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.
removed api-easy tests.
Merge pull request #584 from toolness/api-easy-to-tap

Convert api-easy tests to use tap and request