Stop using alias_method_chain
Stop using alias_method_chain

alias_method_chain was deprecated in Rails 5.0 and removed in 5.1 [1]

Class methods are spilt between two modules because of a RSpec mock
issue [2]. We're using:
  - include: to allow the `alert_survey` method to still be mocked in
    our specs
  - prepend: to allows us to override a method and call `super` to run
    the original implementation of the method in Alaveteli core.

[1] https://github.com/rails/rails/pull/19434
[2] https://github.com/rspec/rspec-mocks/issues/1213

mysociety/whatdotheyknow-theme,mysociety/whatdotheyknow-theme,mysociety/whatdotheyknow-theme