CF-361: add handling of NAST id and saving it as alternateId

Changes are:
* add a Nullable column to store an alternateId. For Cloud Feeds, we are storing the NAST id in the alternateId column
* grab the NAST id from the request header x-tenant-id. Repose will send us 2 since we have mossoId and NAST id. We grab the longest one to be the alternateId.
My PR has been accepted to the 2.4.x branch. But Scalatra 2.4.x is not yet released. So we still have to wait until that release is out.