Removes the need for HA snapshots on cluster join

Slaves now will respond to masterIsAvailable events with slaveIsAvailable
 always. That means that when an instance joins, it will see all the
 availability events that make up the cluster, bringing it up to date.
 This removes the need for snapshot to be received on cluster join.
Ignores TransactionNotPresentOnMasterExceptions

This was done already but not for all cases. Puts that catching in one
place so that all code paths benefit.