Use require_relative for internal requires.
Replace Cane with RuboCop. See #29.
Remove 2.x deprecated APIs.
Ignore local lita_config.rb.
Extract shell adapter event loop into its own method.
Split auth handler methods into smaller pieces.
Reduce method sizes in RackApp.
Reduce method complexity in help handler.
Disable ClassLength and MethodLength cops.
Add RuboCop to the CI build.