Introduced a new Connection Service in the library which abstracts all the Netty...

Introduced a new Connection Service in the library which abstracts all the Netty related code into the Library layer.

The changes here just provides the functionality aspects of the Connection Service and is suitable for a non-osgi environment.
But the code is reorganized (by providing service interface vs implementation and moving them into different package) in lieu
of the upcoming OSGi-friendly library changes.

This commit includes the following changes.

- Removed all the existing code that creates the Netty Channel and replaced it with the new ConnectionService APIs.
- ConnectionService implementation now supports both Active and Passive connection management.
- Added a new ConnectionListener for the Passive connect / disconnect events.
- Split the Library API and impl specific to the Connection management into separate packages.
- Removed all the direct access to OvsDBClientImpl and replaced with its interface OvsDBClient
- Modified all the Integration tests that was using the older method of channel creation to the new ConnectionService mechanism.
- Added a Test for Passive Connection in the Library bundle’s OvsDBClientTestIT class.
- Removed an unused SchemaObjs class
- Renamed file names from OvsDB* to Ovsdb* for the affected classes.

Change-Id: If8a31e4b62cc217f8fe980a5417f35fe53825e26
Signed-off-by: Madhu Venugopal <mavenugo@gmail.com>