2.0.0.0-dev70

* Fixed bugs:
  * Fixed an issue where the schedule of recurring payments was not displayed in the shopping cart
  * Fixed an issue with displaying tax class names in the Customer Groups grid
  * Fixed an issue with testing Solr connection
  * Fixed an issue with using custom module front name
  * Fixed an issue with USPS and DHL usage in the production mode
* Modularity improvements:
  * Consolidated all logic related to Layered Navigation in one separate module
* Framework Improvements:
  * Covered Magento library components with unit tests:
     * Magento/Interception
     * Magento/ObjectManager
     * Magento/Message
     * Magento/Module
     * Magento/Mail
     * Magento/Object
     * Magento/Math
* Updated XML files to include a reference to the schema file in a form of a relative path
* Updated code to be PSR-2 compliant