Changing rake db:schema:dump to run :environment as well as :load_config, as...

Changing rake db:schema:dump to run :environment as well as :load_config, as running :load_config alone will lead to the dumper being run without including extensions such as those included in foreigner and spatial_adapter.

This reverses a change made here: https://github.com/rails/rails/commit/5df72a238e9fcb18daf6ab6e6dc9051c9106d7bb#L0L324

I'm assuming here that :load_config needs to be invoked separately from :environment, as it is elsewhere in the file for db operations, if not the alternative is to go back to "task :dump => :environment do".
Signed-off-by: NJosé Valim <jose.valim@gmail.com>

activerecord/lib/active_record/railties/databases.rake

@@ -341,7 +341,7 @@ db_namespace = namespace :db do
 
   namespace :schema do
     desc 'Create a db/schema.rb file that can be portably used against any DB supported by AR'
-    task :dump => :load_config do
+    task :dump => [:environment, :load_config] do
       require 'active_record/schema_dumper'
       filename = ENV['SCHEMA'] || "#{Rails.root}/db/schema.rb"
       File.open(filename, "w:utf-8") do |file|