Fix issues with export/import in "merge" mode
Additional getters and setters for more consistent behaviour
Merge pull request #2771 from PhantomYdn/export-import-fixes

Fix issues with export/import in "merge" mode
New OrientGraphAsynch implementation supporting parallel execution against the graph by using Futures
Fixed issue #2772
Global Optimiztions
cleenup of record odocument collection listener managment.