Pre Release of major update

This release contains a lot of major changes. All of them were solve issues we found during load testing in a mutlithreaded environment:

• performance optimization using several load tests.
• improved cache performance, reducing overhead
• remove dependency to log4j, implementation of own Logger for time being
• completely rewritten BufferedWriter (used when storing Entities, who are marked with @writebuffer) to use mongo's BulkWriteRequests
• lots of performance tweaks and fixes
• additional tests
• minor changes in API
• some Changes in handling of async operations

this release is not yet ready for production.