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.