WIP: Add reek to detecting ruby code smells

[timurvafin]

Add Reek for detecting code smells in Ruby.
Configuration file stored in config/reek.yml.

Not sure about "Utility Function" smell detector, b/c of basic example of service object is a collection of utility functions.

class ActivateUser
  include Interactor

  def call
    context.activated_user = activate(context.user)
  end

  private

  def activate(user)
    user.update_attributes!(deactivated_at: nil)
    user
  end
end

[vast]

@timurvafin, is there any overlapping checks with rubocop? For example, they definitely both check class/method length. Does it make sense to check for the same things twice?

[timurvafin]

@vast, right. We could disable duplicate checks to minimize support hassle.
Let me check which checks do we really need.