Decouple config and netconf subsystems.

Decouple config and netconf subsystems.

Extract a common mapping for config pusher and config subsystem netconf
Add a ConfigPersisterFacade for XML that allows reads/writes from/to config
subsystem using XML format
Push notifications from YangStoreService to NetconfNotificationManager instead
of using custom listeners
Migrate netconf features from controller features, untangle features

Change-Id: I71e4ca6e0258e0b1f0d6c19119f93eb9d68b7bca
Signed-off-by: Tomas Cere <tcere@cisco.com>
Signed-off-by: Maros Marsalek <mmarsale@cisco.com>
Signed-off-by: Ed Warnicke <hagbard@gmail.com>