Switch Redis driver modules over to oslo.utils.timeutils

This patch changes the Redis drivers so they use the oslo.utils
version of timeutils. This is consistent with the rest of Zaqar.

Change-Id: I56379b90414cbd8bcc6bca6998988dba800693b9
Partially-Implements: blueprint redis-storage-driver
Merge "Switch Redis driver modules over to oslo.utils.timeutils"