Moved cache eviction into logical log.

o Label cache (PersistenceCache) is now evicted from within the logical log
o Schema state is now evicted during logical log application

Notes:

Cache eviction is really tricky right now - again becuse the logical log is not
logical. We should revisit our overall structure around cache eviction, preferrably
after we've moved to a real logical log.

Introduced label cache eviction into the Logical Log application process.

Moved schema state flushing into logical log application.
Refactorings and cleanup of the Kernel

o Updated javadoc for kernel and statement context
o Removed OldBridgingTransactionStateStatementContext
o Renamed TransactionStateStatementContext to StateHandlingStatementContext
o Property keys are now listed through the Kernel

Considerations:

The property key listing is still using NodeImpl and friends, it just
sits down in StoreStatementContext now. We should move to split it up
across the various layers.
moved export code from shell to cypher
added test
added means of exporting labels
added means of exporting index definitions
initial documentation console create scripts now use cypher
fixed some export issues
Sort property keys so that properties appear in a predictable order.
Ensure serial access to a transaction by returning specific error on concurrent requests.

o New test approach for REST transactional API.
o Moved documentation responsibility to TransactionDocTest.
o Centralised URI patterns to TransactionUriScheme.
o Introduced Transaction object that encapsulates transaction id.
Fix asserted message in integration test.
StoreUpgrader minor cleanup.

o Remove unused msgLog field and constructor parameter.
o Use FileSystemAbstraction instead of unsafe java.io.File operations.
Batch inserter support for labels and schema indexes.

o Creating nodes with labels, adding labels and removing labels
o Listing labels for a node
o Creating schema indexes
o Schema indexes are (re-)populated on batch inserter shutdown
o Support for all the above, except creating new schema indexes,
  in the Batch Database