Clean up of packages, resolves many circular dependencies.

No functionality changes, only moving classes to correct packages.

o Move UpdateMode to the index component, resolves all but one remaining circular dependency in the new kernel code.
o Moved ThreadToStatementContextBridge into core along with the NodeManager and friends, removes 44 circular package dependencies.
o Moves kernel implementation classes into the impl package and away from the kernel API.
o Deletes a few unused classes.
Auto flushes the logger for every line added, instead of waiting for the buffer to fill before seeing that chunk of messages
Moved state-handling operations interfaces into kernel impl, since they are not part of the API.
Identify Neo4jDesktop in UDC.
Added test cases for merge with maps.

Should be able to assign a map of properties to a merged node ON CREATE,
and this map of properties should be able to contain the property we
merged on, even if a uniqueness constraint exists for that property.
Fix faulty import line.
Suspends the transaction in a finally block

since we must uphold the contract where the transaction must have been
suspended no matter what happens before leaving that method.
Removed unnecessary deprecation annotations
Throws more specific exceptions from TxManager#resume

There are two possible failures that can happen in #resume:
 (1) The current thread has already got another transaction associated with it
 (2) The transaction to be resumed is already associated with another thread

These two failures got their own exceptions: ThreadAssociatedWithOtherTransactionException and
TransactionAlreadyActiveException so that callers can react appropriately
to the two scenarios. Typically there's special handling of (2). Doing
this made UnableToResumeTransactionException redundant, and it was too
generic to begin with as it represented both (1) and (2).

This commit also tidies up and corrects logging regarding old transactions
on the master which are to reaped, so less logging and more relevant
logging there.