Bug 1029: Remove dead code: sal-data-api

opendaylight/md-sal/sal-data-api is dead code that is not being
built and hasn't for some time.  Its complicating keeping
versions up to date and verifying that they are up to date.

If it needs to be revived in the future it can be retrieved
from git.

Change-Id: I28d9a8f63ff0398766d0d8c29f18a27d75642d2e
Signed-off-by: Ed Warnicke <eaw@cisco.com>
Merge "Bug 1029: Remove dead code: sal-data-api"