Creating Product component from VariableProductBundle and ProductBundle classes

Conflicts:
	src/Sylius/Bundle/CoreBundle/Resources/config/doctrine/model/OrderItem.orm.xml
	src/Sylius/Bundle/CoreBundle/Resources/config/doctrine/model/VariantImage.orm.xml
	src/Sylius/Component/Product/Builder/ProductBuilder.php
	src/Sylius/Component/Product/Builder/PrototypeBuilder.php
	src/Sylius/Component/Product/spec/Sylius/Component/Product/Builder/ProductBuilderSpec.php
	src/Sylius/Component/Product/spec/Sylius/Component/Product/Builder/PrototypeBuilderSpec.php
Updating composer.json for product component and bundles
Initial Variation and Attribute implementations
Fix promotion events class name
Fix typo in class name
Fix reported issues
Merge pull request #1308 from Sylius/product-component

[WIP] Initial implementation of Attribute and Variation components & bundles