2.0.0.0-dev63

* Modularity improvements:
  * Consolidated all PayPal-related logic in a separate module
  * Resolved dependencies on the Magento_GroupedProduct module
  * Added the ability to enable/disable/remove the Magento_GroupedProduct module without impact on the system
* Implemented the Oyejorge Less.php adapter
* Implemented the Less files importing mechanism
* Added the ability to configure certain cache frontend, and associate it to multiple cache types, thus avoiding the duplication of cache configuration
* Implemented the more strict format of array definition in the DI configuration:
  * Covered array definitions with XSD, and made the whole DI configuration validated with XSD
  * Added the ability to define arrays with keys containing invalid XML characters, that was impossible when keys were represented by the node names
* Fixed bugs:
  * Fixed an issue with missed image for a cron job for the abandoned cart emails
  * Restored the ability to configure cache storage in `local.xml`
  * Fixed an issue with the css\js merging functionality
  * Fixed an issue with customer selection on the order creation page
* AppInterface renamed to LauncherInterface
* Removed the reinit logic from the Config object
* Framework part of the "URL" functionality removed from modules
* Framework part of the "Config" functionality removed from modules
* Removed the deprecated EAV structure creation method from the EAV setup model
* Updated various PHPDoc with parameter and return types
* Indexer implementation:
  * Implemented a new indexer structure
* Refactored Web API Framework to support the Data Object based service interfaces
* Refactored controllers, blocks and templates of the Sales module to use Customer service
* GitHub requests:
  * [#275] (https://github.com/magento/magento2/issues/275) -- XSS Vulnerability in app/code/core/Mage/CatalogSearch/Block/Result.php
* Removed the outdated Customer service