Add a new header flag for "migrated with data" and set this to 1

Add a new header flag for "migrated with data" and set this to 1
when we migrate a non-empty record onto the node
or a non-empty record off the node

When we migrate a record back to the lmaster and yield the dmaster role,
inspect this flag if if it is still not set, we can delete the record from
the local database as soon as we have migrated it back to the lmaster.