Reset Capybara's monkey patch on old versions.

Apps just upgrading to RSpec 3 are more likely to have several
conditions which may cause a poor user experience:

- Version of Capybara prior to 2.4.0
- Loading Capybara before rspec-rails in `spec/spec_helper.rb`
- Not enabling monkey patch mode or have set:

  `config.expose_dsl_globally = false`

When these conditions are all met our `feature` alias is exposed
globally overwriting the Capybara monkey patch. This will cause all
feature specs to be skipped.

For a user attempting to upgrade an app this can be a very frustrating,
and confusing, "bug".

lib/rspec/rails/example/feature_example_group.rb

@@ -46,17 +46,27 @@ def visit(*)
     EOT
   }
 
+  # Capybara's monkey patching causes us to have to jump through some hoops
+  top_level = self
+  main_feature = nil
   if defined?(Capybara) && ::Capybara::VERSION.to_f < 2.4
     # Capybara 2.2 and 2.3 do not use `alias_example_xyz`
     opts[:skip] = <<-EOT.squish
       Capybara < 2.4.0 does not support RSpec's namespace or
       `config.expose_dsl_globally = false`. Upgrade to Capybara >= 2.4.0.
     EOT
+    main_feature = top_level.method(:feature) if top_level.respond_to?(:feature)
   end
 
   RSpec.configure do |c|
+    main_feature = nil unless c.expose_dsl_globally?
     c.alias_example_group_to :feature, opts
     c.alias_example_to :scenario
     c.alias_example_to :xscenario
   end
+
+  # Due to load order issues and `config.expose_dsl_globally?` defaulting to
+  # `true` we need to put Capybara's monkey patch method back. Otherwise,
+  # app upgrades have a high likelyhood of having all feature specs skipped.
+  top_level.define_singleton_method(:feature, &main_feature) if main_feature
 end