remove test helper serverTearDown (~> this.server.tearDown(done) in tearDowns); add arg 'done' to test helper createProxyBackend; renamed backend.close to backend.tearDown
add optionally passing a fn to test helper createServer; use this in http-proxy-test.js
add (local) helper function serverTearDown to resource-middleware-test.js s.t. we get back the concise tearDowns
tests: instead of an additional var from 'buster.countdown(x, done)' we're overwriting 'done' itself - prevents from accidentally using done again
fix test: must not combine, 'done(..)' and within ".." call done again (or stuff from countdown(x, done)