Added new toolbox component for starting Neo4j server in integration tests.

- Introduces TestServerBuilder, which is meant to replace the public
  ServerBuilder API.
Make the change trackers in NodeManager thread-safe
Merge pull request #3327 from chrisvest/1.9-disable-omit-stacktrace

Disable the OmitStackTraceInFastThrow JVM feature
Merge pull request #3244 from jakewins/2.1-servertest

Added new toolbox component for starting Neo4j server in integration tests
Merge pull request #3320 from chrisvest/1.9-threadsafe-trackers

Make the change trackers in NodeManager thread-safe
Merge remote-tracking branch 'upstream/1.9-maint' into 2.0-maint

Conflicts:
	community/kernel/src/main/java/org/neo4j/kernel/impl/core/NodeManager.java
Merge branch '2.0-maint' into 2.1-maint

Conflicts:
	community/kernel/src/main/java/org/neo4j/kernel/impl/core/NodeManager.java
Merge branch '2.1-maint'

Conflicts:
	community/kernel/src/main/java/org/neo4j/kernel/impl/core/NodeManager.java
Moved Digests to community/io, since TargetDirectory moved there