Fix yanglib SFT failure

Fix yanglib SFT failure

For some reason the YangLibRestApp doesn't get created which causes
BP to timeout b/c it advertises an OSGi service referenced by the
BP xml. Instead of using a service I changed it to use a static
to bridge between BP and the web app, as is done elsewhere.

Change-Id: Ia606514258d2082bf041ac81ab890f53f999ee2c
Signed-off-by: Tom Pantelis <tompantelis@gmail.com>
(cherry picked from commit c734a43d922f4603c0463e6de86c99f0ca317887)