Added new metrics to track.

Added these additional OIDs:
	redisBlockedClients,
	redisEvictedKeys,
	redisExpiredKeys,
	redisKeyspaceHits,
	redisKeyspaceMisses,
	redisPubsubChannels,
	redisPubsubPatterns,
	redisUptime,
	redisUsedMemoryRss

The perl script has been updated, as well as the MIB.  In addition, I
cleaned up some typos (such as claiming that this is a MySQL monitoring
project) and added "UNITS" to some of the OIDs.
Gentoo support: added init.d and conf.d files.

These will need to be deployed to:
   /etc/init.d/redis-snmp
   /etc/conf.d/redis-snmp