SeQura code style guide and shared configuration.

Add this line to your application's Gemfile (we need to point to GitHub since it's not published):

gem "sequra-style", git: "https://github.com/sequra/sequra-style", require: false

And then execute:

$ bundle install

Use the following directives in a .rubocop.yml file:

inherit_gem:
  sequra-style:
    - default.yml