the neostore data source had been started internally. The db would be in a
state where it would need recovery for the neostore data source, as well as some
other data source. This would fail since eventually TxManager#getTransaction()
would be called, which would fail since it hadn't as of yet recovered fully.
Whereas that failure would happen in a listener and merely be logged, one effect
of it would be that there would seem to be no relationship types in the database.

Head returns null on empty collection, Tail returns empty.

Issue #922 write logging messages to stdout only when the logger is not defined.

Fixed typo when building up the deadlock detected message casuing the wrong transaction to appear in the cycle.

Improvements and changes for various components, driven by the High Availability architectural changes

* XaDataSources implement Lifecycle. That allows them to be started and
   stopped in a more controlled fashion and through the LifeSupport present
   in XaDataSourceManager
* TxManager now does recovery by scanning the TxLog and waiting for data
   sources with pending txs to register - then proceeds to recover. It
   is no longer triggered externally.
* Introduces the Listener classes and support for more uniformly managing
   Listeners in Neo4j
* Removes LastTxIdSetter - no longer necessary with the removal of
   ZooKeeper
* Changes in configuration to support new settings types, like
   HostnamePortSetting
* Moves Setting back to type parameterized GraphDatabaseSetting
* Kernel extensions are now factories and factories create instances
   that participate in the database lifecycle
* IdGeneratorFactories no longer use highestIdInUse or startup ad
   arguments in their methods
* Refactored TransactionInterceptors to more centrally manage their
   instantiation and configuration
* NeoStoreXaDataSource creation can be deffered
* LockManager is now an interface, with a default implementation of
   LockManagerImpl

Authors: Anders Nawroth, Johan Svensson, Mattias Persson, Rickard Oberg, Chris Gioran

  Expressions used to be functions that, given a map of String->Object, returned
  a value. This lead to problems with parameters, which had to be encoded using
  magic strings in the map. Now an Expression takes an ExecutionContext instead,
  which allows parameters to be stored side by side with the result.

o Refactoring of how named paths are treated in the Query object
  Patterns are now duplicated - if a named path is declared, the pattern items it
  contains will be placed both in the named path field, but also in the patterns
  field. This is because named paths can come from multiple places these days, not
  only from matching.

adding batchinserter autoindex test

Now, we throw an appropriate exception if we run out of disk while writing the logical log, and that exception
ends up getting handled by a more elaborate error handling mechanism in the tx manager.

We also refactored the XaLogicalLog, such that the strategy for copying transactions over to a new log during rotation
is handled by it's own class, covered with a unit test. This let us remove one of the breakpoint-based tests from the neo4j
subproject.

This commit will be followed by a second refactoring later this or next week where all usages of FileChannel.write will
recieve the same protection that we added in the LogicalLog implementation.

Added some information on id resuse. Got rid of outdated links. Got the server security chapter in better shape.

write logging messages to stdout only when the logger is not defined as opposed to when the logging level is not enabled.

upgrading chrome driver and selenium for OSX

another optional MATCH.