Instance object incorrectly handles None info_cache

1) When getting records from the DB, it's possible for info_cache to be
None, but this case was ignored.
2) When de-serializing Instance with a None info_cache, a traceback
would occur.

Fixes bug 1228426

Change-Id: I60e610aeafc9dea8d832adec10baaaecbae75215
Merge "Instance object incorrectly handles None info_cache"