webosvbox: Look for default image in local dir first

[GF-1981] Arrange for image build recipe to copy webosvbox script into
deploy/images.

Open-webOS-DCO-1.0-Signed-off-by: Yegor Minin <yminin@luxoft.com>
Change-Id: Iaf2ddbc920ecf49d66a7b437cf9627a1d05151d7
Reviewed-on: https://g2g.palm.com/1729
Reviewed-by: Build Verification
Reviewed-by: Keith Derrick <keith.derrick@lge.com>
Reviewed-by: Susan Montooth <susan.montooth@lge.com>
Tested-by: Yegor Minin <yminin@luxoft.com>