Use dom-parent internally

Use dom-parent internally

dom-parent is essentially an mdsal-level bundle-parent, as it
inherits from bundle-parent and brings in dependencyManagement
we (and our downstreams) need.

Reuse this parent pom across the project, so that we do not have
to repeat dependencyManagement over and over again.

Change-Id: I0575ef37d2eedcd7cda0c69d6dcec3a65af64cf3
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>