Initial code drop of yang model driven configuration system

Initial code drop of yang model driven configuration system

Configuration system employs two phase commit to validate and push configuration changes to a running system. It allows changing simple attributes, complex transfer objects, and also provides dependency injection between configured modules.
Module config-api contains base yang model config.yang, defining language extensions and other elements required by all configuration models. Other than that it contains both apis implemented by config-manager and spis to be implemeted by configuration providers. Since the configuration system is internally driven by JMX, package org.opendaylight.controller.config.api.jmx contains all M(X)Bean interfaces exposed by config-manager.
Module config-manager is implementation of config-api.
Module config-util contains clients (both JMX and jolokia, which is http based bridge to JMX) of configuration system.
Module yang-jmx-generator parses yang models and creates java representation of configuration models and service interfaces.
Module yang-jmx-generator-plugin is connector to yangtools yang-maven-plugin that generates skeletons of java files needed by configuration providers.
Module yang-test contains example yang file, from which code is being generated.
Module yang-jmx-generator-it tests yang-test.
Module yang-store-api contains api for a registry of all yang models parsed by yang-jmx-generator.
Module yang-store-impl uses OSGi extender pattern to read META-INF/yang/*.yang from all bundles and provides snapshot view of currently available configuration models.

Change-Id: Icf3201f9754e4ca28ebce3411d2a667dcd7e75c8
Signed-off-by: Tomas Olvecky <tolvecky@cisco.com>