Refactor tests, classes and methods and configuration options to toggle modules.

* Configuration option is now available under modulestatus that have the options to enable/disable Vafwheel, Vaftire and Vafwheeladapter. This can save loading time if the modules are not required for some Magento E-commerce stores.
* Extended the VF_TestCase up to Elite_TestCase and moved needed Magento test case methods to Elite_TestCase where they belong.
* Extended VF_AbstractSingleton to Elite_Vaf_Singleton for the logic of finding if a module should be enabled/disabled based on the configuration option in config.ini/config.default.ini
* Elite_Vaf_Singleton extends the parent method flexibleSearch() and adds needed logic to call the needed Vafwheel/Vaftire/Vafwheeladapter modules to extend functionality of the enabled modules. If the module is enabled in the configuration but it cannot be found in the ELITE_PATH, an exception is thrown at runtime.
* Elite_Vaf_Singleton extends ensureDefaultSectionsExist and adds a call to ensure that the new configuration option called modulestatus exists as a section.
* Elite_TestCase over VF_TestCase for using the correct methods for the Magento Test Suite. 
* Bumped module versions to v2.1-build1 and modified composers branch-alias to 2.1.x-dev