Slave goes through 'switchToSlave' process on every 'masterIsElected' event
Fixes an issue which made it impossible to resume a migration

i.e. when the migration had been completed, and the migration aborted...
when it would be picked up again the next time to do the moving of files
from migration directory to store directory there would be an assumption
that the "migrate" method would have been run before it. This led to an
NPE for an uninitialized field.
Updates changelogs for 1.9.9 with last batch of changes
Merge pull request #3252 from tinwelint/2.1-resume-migration-fix

[2.1] Fixes an issue which made it impossible to resume a migration
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
Merge branch '2.0-maint' into 2.1-maint

Conflicts:
	enterprise/backup/CHANGES.txt
Tagging for version 1.9.9
Back to development version.
Updates poms to 1.9.10-SNAPSHOT
TxManager used to commit/rollback transactions
Merge pull request #3295 from lutovich/2.0-lock-release-during-db-shutdown

[2.0] TxManager used to commit/rollback transactions
Tweak for number of files opened by Lucene
Merge pull request #3302 from lutovich/2.1-reduce-number-of-opened-files

Tweak for number of files opened by Lucene
Consider all possible result types from `CASE`

Rather than finding the leastUpperBound between all the different
expression types, consider them all as equal possibilities.
Merge commit '4d0c1e24d2c660891b656ec25405baf3d33677be' into merge-2.0-to-2.1

Conflicts:
	community/kernel/src/main/java/org/neo4j/kernel/TopLevelTransaction.java
Merge pull request #3316 from lutovich/merge-2.0-to-2.1

Merge 2.0 to 2.1
Merge remote-tracking branch 'upstream/2.0-maint' into 2.1-maint

Conflicts:
	community/cypher/cypher-compiler-2.1/src/test/scala/org/neo4j/cypher/internal/compiler/v2_1/ast/CaseExpressionTest.scala
	community/cypher/cypher/src/test/scala/org/neo4j/cypher/FunctionsAcceptanceTest.scala
Move config for the manual to doctools.
Follow-up on moving the manual to neo4j.com/docs.