task/ta-npe-001-12 -- update job_item.notify_ts for customer comms

nparcel/primaryelect.py
* update the process() method to update the job_item.notify_ts column

nparcel/table/jobitem.py
* update the schema() method to include the new column, notify_ts
* new method update_timestamp_sql() which updates a datetime
  based column
* new method update_notify_ts_sql() which provides an SQL to update
  the job_item.notify_ts column
* refactor update_reminder_ts_sql() method to use the generic
  update_timestamp_sql() method