Make HA fail to start with old store
Make slave fail when master have different upgraded store
StoreId contains upgrade info and is broadcasted to the whole cluster, slave checks all StoreIds on startup
Handling of exceptional conditions during HA upgrade
Merge remote-tracking branch 'upstream/2.1-maint' into 2.1-ha-upgrade
Merge pull request #2979 from lutovich/2.1-ha-upgrade

2.1 ha upgrade