v7.0.0

Rename Master to Leader (#323)

While no underlying functionality has changed, this is a breaking change due to the new names of events/emitters

• Updated effected event handlers from master to leader
• Updated README.md to reflect the change from master to leader
• Any changes to import statements are them being reordered via TypeScript Hero
• Fixed typo in __tests__/utils/specHelper.ts, object was named SpecHeloer, changed to SpecHelper

Docker examples (#321)

• Adds examples of how to properly start and stop node-resque processes in docker.
• An accompanying blog post can be found here: https://blog.evantahler.com/production-node-applications-with-docker-3-devops-tips-for-shutting-down-properly-ed54f09f0a7f