make datastore_version_id required

The datastore addition didn't migrate existing instances,
which causes existing installations to blow up after upgrading.
This commit addresses that by inserting best-guess dummy data
into the db.  Operators will need to clean up the values to match
their actual usage.

Change-Id: I7ae064cea9b654a4501b91877b779fb4073623af
Closes-Bug: #1259642
Merge "make datastore_version_id required"