Remove support for Redis 1.2.

Actually we have just removed the server profile so nothing stops you
from reimplementing it, but Redis 2.0 has been released 4 years ago so
we are speaking of ancient releases that should probably not even be
used anymore.
Fix bug when checking for support for the UNWATCH command.
Remove parsing of allocation stats from responses to INFO.

The allocation stats section was most likely something available in
betas of some older release of Redis, it is not even reported on the
official documentation.