Added Gemfile, added rubocop.  Used rubocop to correct whitespace issues in almost every file.
rubocop: Removed trailing blank lines.
rubocop: Used preferred collection methods.
Rubocop: Avoid double negation.
rubocop: Fixed empty lines.
rubocop: Use even? and odd?.
rubocop: Single line if modifiers.
rubocop: Used new lambda syntax.
rubocop: Comments should have a leading space.
rubocop: Tackled lines longer than 120 characters that did not need to be.
Rubocop: When defining operator method, name argument 'other'
rubocop: Got rid of a bunch of parentheses for 'let' calls that I did not need.
rubocop: Use %w() instead of %w{}.
rubocop: Fixed redundant returns.
rubocop: Fixed redundant self.
rubocop: Added some spaces around things.
rubocop: Used single-quoted strings if possible.
Finished rubocopping.  Removed the rubocop-todo.yml.
rubocop: Enable the DoubleNegation cop.
rubocop: Lock it to a specific version because they make breaking changes.