Fix bugs and add Product prices export
	modifié:         core/lib/Thelia/Config/Resources/export.xml
	modifié:         core/lib/Thelia/Controller/Admin/ImportController.php
	modifié:         core/lib/Thelia/Core/DependencyInjection/Loader/XmlFileLoader.php
	modifié:         core/lib/Thelia/Core/DependencyInjection/Loader/schema/dic/config/thelia-1.0.xsd
	nouveau fichier: core/lib/Thelia/ImportExport/Export/Type/ProductPricesExport.php
	modifié:         core/lib/Thelia/Tests/Controller/ImportControllerTest.php
Refactor ProductPriceImport -> ProductPricesImport
	modifié:         core/lib/Thelia/Config/Resources/import.xml
	renommé:         core/lib/Thelia/ImportExport/Import/Type/ProductPriceImport.php -> core/lib/Thelia/ImportExport/Import/Type/ProductPricesImport.php
	modifié:         core/lib/Thelia/Tests/ImportExport/Import/ProductPriceImportTest.php