Add mdsal-model-artifacts to binding-parent

Add mdsal-model-artifacts to binding-parent

Given the migration to use the MD-SAL project, dependencies like
ietf-inet-types and ietf-yang-types are now imported via
org.opendaylight.mdsal.model instead of org.opendaylight.yangtools.model
groupId. However, the dependency management section of the
binding-parent does not include mdsal-model-artifacts, where the
previously mentioned artifacts are declared. This breaks imports in
bundles inheriting from binding-parent.

Change-Id: Id19c36862f8ab8bbfa70f8a538619070cf8814d7
Signed-off-by: Florin Coras <fcoras@cisco.com>