Minor fixes

D2TreeCore.java
* formatting improvements
* forwardRedistributionResponse(Message): Now using movePivot method to move pivot instead of separate code.
* movePivot(Message): bucketSize not taking surplus nodes into account is now fixed.
* Transfer: moved a couple lines of link creating code to TransferResponse.
* *  Dest bucket <-> new last node of its bucket
* * Pivot bucket <-> new first node of its bucket

PrintMessage.java
* removed directory path from messages to make them more compact
Basic Index Structure implementation

D2TreeIndexCore.java
* Implemented lookup, insert and delete methods.

D2TreeCore.java, RoutingTable.java
* Minor cleanup and format improvements.

Misc
* New message type VWUpdateRequest.
* New message type VWUpdateResponse.
* D2TreeMessageT: New message types added for element lookup, insert and delete.