Separate boss and worker executors in Client
Fix RebuildCountsTest on Windows

- it was caused by a problem with non absolute path in the EphemeralFileSystemAbstraction
Fix test errors
Merge pull request #3412 from lutovich/1.9-flaky-TestCommunication

Separate boss and worker executors in Client
Merge remote-tracking branch 'upstream/1.9-maint' into 2.0-maint

Conflicts:
	enterprise/com/src/main/java/org/neo4j/com/Client.java
Merge branch '2.0-maint' into 2.1-maint
Merge branch '2.1-maint'

Conflicts:
	enterprise/com/src/main/java/org/neo4j/com/Client.java
Sorts and dedups label ids in batch importer