Fix property ownership revisit bug in ConsistencyChecker

The consistency checker would mistakenly think that a previously determined owner was a duplicate of itself, when `consistency_check_property_owners` was enabled, leading to many false positives.

This fixes #3275
Merge pull request #3364 from chrisvest/2.1-consistency-ownership-revisit

Fix property ownership revisit bug in ConsistencyChecker
Document the Neo4j Harness library for testing unmanaged extensions
Make ExecutionEngine available to users of Unmanaged Extensions.

- Small doc change to show how to get ExecutionEngine.
Merge pull request #3368 from jakewins/2.1-harnessdoc

Document the Neo4j Harness library for testing unmanaged extensions
Merge pull request #3370 from jakewins/2.1-ee-server

Make ExecutionEngine available to users of Unmanaged Extensions.
Merge branch '2.1-maint'

Conflicts:
	community/consistency-check/src/test/java/org/neo4j/consistency/checking/full/ExecutionOrderIntegrationTest.java
	community/consistency-check/src/test/java/org/neo4j/consistency/checking/full/FullCheckIntegrationTest.java
	community/server-examples/LICENSES.txt
	community/server-examples/NOTICE.txt
	community/server/src/main/java/org/neo4j/server/AbstractNeoServer.java