Default to `development` path when HIREFIREAPP_TOKEN isn't present.
Use new counting logic used in HireFire 2 for Resque. This commit changes the counting logic from counting only the current queue size (which decreases the moment a job is popped off the queue) to counting the current queue size combined with the amount of workers that are currently processing jobs. This should fix the issue where workers that were still processing jobs would've been killed. They will no longer be killed until they finish processing their jobs.
Releasing version 0.2.0.