Stringify firmware datetime
Stringify firmware datetime

With the change to msgpack, datetime objects cannot be serialized.  Apply
tlvdata compliant transform before storing.

xcat2/confluent,jjohnson42/confluent,jjohnson42/confluent,jjohnson42/confluent,jjohnson42/confluent,xcat2/confluent,xcat2/confluent,jjohnson42/confluent,xcat2/confluent,xcat2/confluent