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.
Remove the Java5 compatibility service loader.

It should never be used anyway, since we now depend on Java 7.
Merge pull request #3368 from jakewins/2.1-harnessdoc

Document the Neo4j Harness library for testing unmanaged extensions
Remove our own service loader implementation

It is most likely never used.
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
Merge pull request #3376 from chrisvest/2.2-remove-legacy-service-loader

Remove the Java5 compatibility service loader.
Expose a way to ask a lucene index to sample index selectivity

o Scan a sample of index entries and compute uniqueSampledValues / sampleSize
Add a new CountsKey for index entry counts
Maintain index update counts from index proxies

o OnlineIndexProxy will ensure that the index counts are updated
o Fix bug when generate LazyIndexUpdates to never construct 'overlapping updates'
o Cleanup code in LazyIndexUpdates
o Make sure we update index update counts during population
Add minor version to CountsStore such that we can flush safely on index flip (outside of log rotation)

o Ensure we compare CountsKeys correctly by type
o Fix reading of index keys
o Add flushIndexCounts() to IndexStoreView
Remove index counts when dropping an index
Make index stats part of SchemaRead and add indexNumberOfEntries

Rationale: For planning to be sane, indices shouldn't appear or disappear out of nowhere, hence we need to be tied to the schema read lock
Add IndexStatisticsTest
Pass on transaction id to index updaters
Pull out and refactor IndexCountVisitor from CountingIndexUpdater
Only apply index count updates for unprocessed transactions during recovery

o Rename updateXYZ to incrementXYZ CountsStore related methods
o Push transactionId down to IndexUpdaters (and couple them to process only updates for a single transaction)