Add dependency on javax.validation validation-api

Add dependency on javax.validation validation-api

In order to upgrade to org.eclipse.persistence to 2.6.0+ in odlparent,
downstream consumers must include the dependency on javax.validation
validation-api version 1.1.0.Final as described here:

http://stackoverflow.com/questions/28568154/
how-to-get-eclipselink-2-6-0-m3-working-with-jersey-1-18-3

The work to upgrade odlparent's moxy version is included in this patch:
https://git.opendaylight.org/gerrit/#/c/37541/

Change-Id: Ia3dc42c498a334d36fefb49fe7ddb936638987b7
Signed-off-by: Ryan Goulding <ryandgoulding@gmail.com>