Fix minor typo in spec
Merge pull request #25 from andyw8/fix-minor-typo-in-spec

Fix minor typo in spec
Remove unnecessary `require 'spec_helper'` calls

No longer needed in RSpec 3 since this can
be specified in the project's `.rspec` file.
Merge pull request #27 from andyw8/remove-spec-helper-requires

Remove unnecessary `require 'spec_helper'` calls
Add VerifiedDoubles cop
Merge pull request #26 from andyw8/verified-doubles

Verified doubles
Fix spelling: `emtpy` -> `empty`
Merge pull request #28 from andyw8/fix-spelling-of-empty

Fix spelling: `emtpy` -> `empty`
Adapt code to new rubocop version