Analytics workaround for non production environments

This has solution has been tested with Hyrax 1.0.0.rc1

Legato, the Google Analytics API gem used by Hyrax, depends on the eager loading of models extended by Legato::Model. This is a problem in development environments where models are not eagerly loaded.

If you are running into this problem, you would be seeing an error like this when you try to view a work's analytics page:

ActionView::Template::Error (undefined method `hyrax__pageview' for #<Legato::Management::Profile:0x007fc8ee884a78>):
    1: <!-- Adapted from jquery-flot examples https://github.com/flot/flot/blob/master/examples/visitors/index.html -->
    2: <%= javascript_tag do %>
    3:   var hyrax_item_stats = <%= @stats.to_flot.to_json.html_safe %>;
    4: <% end %>
    5: 
    6: <%= content_tag :h1, @stats, class: "lower" %>
  
hyrax (1.0.0.rc1) app/models/hyrax/statistic.rb:36:in `ga_statistics'
hyrax (1.0.0.rc1) app/models/hyrax/statistic.rb:51:in `combined_stats'
hyrax (1.0.0.rc1) app/models/hyrax/statistic.rb:24:in `statistics'
hyrax (1.0.0.rc1) app/presenters/hyrax/work_usage.rb:27:in `pageviews'
hyrax (1.0.0.rc1) app/presenters/hyrax/work_usage.rb:20:in `to_flot'

In order to test Hyrax's google analytics integration in development, add the following initializer to your application at config/initializers/legato.rb:

Rails.application.config.after_initialize do
  # If Google Analytics are enabled, pre-load the models which rely on
  # Legato::Model.extended(base) dynamic profile method generation. Non-production
  # environments wouldn't necessarily have this eager loaded by default.
  if Hyrax.config.analytics
    require 'legato'
    require 'hyrax/pageview'
    require 'hyrax/download'
  end
end

This initializer is not needed in production environments.

These instructions were adapted from this ticket: https://github.com/projecthydra/sufia/issues/2460