Allow adding per-environment custom settings

Until now, when editing a specific environment, other CONSUL
installations had to edit the original file, which made it harder to
upgrade.

Now it's possible to change the default CONSUL settings using custom
files, making it easier to upgrade to versions of CONSUL which change
the original environment files (which is very common when upgrading
versions of Rails).

config/environments/custom/development.rb

@@ -0,0 +1,4 @@
+Rails.application.configure do
+  # Overwrite settings for the development environment or add your own
+  # custom settings for this environment.
+end

config/environments/custom/preproduction.rb

@@ -0,0 +1,4 @@
+Rails.application.configure do
+  # Overwrite settings for the preproduction environment or add your own
+  # custom settings for this environment.
+end

config/environments/custom/production.rb

@@ -0,0 +1,4 @@
+Rails.application.configure do
+  # Overwrite settings for the production environment or add your own
+  # custom settings for this environment.
+end

config/environments/custom/staging.rb

@@ -0,0 +1,7 @@
+Rails.application.configure do
+  # Overwrite settings for the staging environment or add your own
+  # custom settings for this environment. Note these changes will
+  # also affect the preproduction environment, so edit the
+  # `config/environments/custom/preproduction.rb` file if you don't
+  # want these changes to be applied there as well.
+end

config/environments/custom/test.rb

@@ -0,0 +1,4 @@
+Rails.application.configure do
+  # Overwrite settings for the test environment or add your own
+  # custom settings for this environment.
+end

config/environments/development.rb

@@ -71,3 +71,5 @@ Rails.application.configure do
   # routes, locales, etc. This feature depends on the listen gem.
   # config.file_watcher = ActiveSupport::EventedFileUpdateChecker
 end
+
+require Rails.root.join("config", "environments", "custom", "development")

config/environments/preproduction.rb

@@ -1 +1,2 @@
 require Rails.root.join("config", "environments", "staging")
+require Rails.root.join("config", "environments", "custom", "preproduction")

config/environments/production.rb

@@ -122,3 +122,5 @@ Rails.application.configure do
   # config.active_record.database_resolver = ActiveRecord::Middleware::DatabaseSelector::Resolver
   # config.active_record.database_resolver_context = ActiveRecord::Middleware::DatabaseSelector::Resolver::Session
 end
+
+require Rails.root.join("config", "environments", "custom", "production")

config/environments/staging.rb

@@ -121,3 +121,5 @@ Rails.application.configure do
   # config.active_record.database_resolver = ActiveRecord::Middleware::DatabaseSelector::Resolver
   # config.active_record.database_resolver_context = ActiveRecord::Middleware::DatabaseSelector::Resolver::Session
 end
+
+require Rails.root.join("config", "environments", "custom", "staging")

config/environments/test.rb

@@ -61,3 +61,5 @@ Rails.application.configure do
     end
   end
 end
+
+require Rails.root.join("config", "environments", "custom", "test")