DSP-1568: Use CL.QUORUM for all auth related queries

Also insert the default superuser with explicit timestamp
of 0 to reduce the chance of its accidental recreation.
DSP-1568: Delay superuser setup by 10 seconds

We can do it safely since it's a once-in-a-cluster-liftetime
event thing. This makes accidental superuser recreation even
less likely.
Merge pull request #27 from riptano/DSP-1568

Dsp 1568