fixes concurrency issue due to shared instance variable for JsonGenerator #955
Merge pull request #957 from jexp/955

Eyeballed this, seems sane.
Add tests that clarify the semantics of DiffSets.apply

o DiffSets.apply now filters out added elements from source, too
Merge remote-tracking branch 'origin/master' into 2.0

Conflicts:
	advanced/server-advanced/src/main/java/org/neo4j/server/advanced/modules/JMXManagementModule.java
	community/server/src/main/java/org/neo4j/server/database/CommunityDatabase.java
	community/server/src/main/java/org/neo4j/server/modules/RESTApiModule.java
	community/server/src/test/java/org/neo4j/server/WrappingNeoServerBootstrapperDocIT.java
	community/server/src/test/java/org/neo4j/server/database/EphemeralDatabase.java
	community/server/src/test/java/org/neo4j/server/database/TestCommunityDatabase.java
	community/server/src/test/java/org/neo4j/server/helpers/ServerBuilder.java
	community/server/src/test/java/org/neo4j/server/helpers/ServerHelper.java
	community/server/src/test/java/org/neo4j/server/modules/RESTApiModuleTest.java
	enterprise/server-enterprise/src/test/java/org/neo4j/server/enterprise/TestEnterpriseDatabase.java
	enterprise/server-enterprise/src/test/java/org/neo4j/server/enterprise/functional/EnterpriseServerIT.java
	packaging/qa/src/test/java/org/neo4j/qa/features/StartAndStopFeatureTest.java