#5 slave monitoring and load balancing

[B. D. Lambert]

The slave monitor should send back CPU load in the last 1, 5, and 10 min, etc, instead of a raw CPU time. Master should use the CPU load, and possibly disk and network load for load balancing, rather than number of active transactions. The latter is a not a good indication of system load, and it is dangerous to prevent slaves with dangling transactions from being used again.