Slave goes through 'switchToSlave' process on every 'masterIsElected' event
Updates changelogs for 1.9.9 with last batch of changes
Merge pull request #3217 from lutovich/1.9-slave-epoch-mismatch

[1.9] Slave goes through 'switchToSlave' process on every 'masterIsElected' event
Merge branch '1.9-maint' into 2.0-maint

Conflicts:
	enterprise/backup/CHANGES.txt
	enterprise/ha/src/test/java/org/neo4j/ha/TestSlaveOnlyCluster.java