feat(core): Add app.setup and app.teardown hook support

[daffl]

This pull request adds built-in support for application setup and teardown hooks. They are special hooks that don't run on the service level but instead directly on app.setup and app.teardown

app.hooks({
  setup: [ mongodbConnection ],
  teardown: [ closeMongoConnection ]
});

[marshallswain]

🚀