refactor(env): define NODE_ENV in config
fix(*): fix `assert.ok` and remove function names
fix(logger): remove assertion of `topic` argument

When the `logger` function is called (e.g. `var logger =
require(./lib/log')('app');`), the NODE_ENV variable is not yet
initialised. As a result, the custom `assert.ok` function skips the
assertion.
fix(User): `spark` is `null` when restoring