Initial implementation of transactions
Refactored models: all functionality is back in their original model classes.
Added a few basic integration tests for the transactions concept.
Added more integration tests
Implemented first concept of a concurrent ConfigManager.
Improved thread-safety, and performance of concurrent requests.
Added JavaDoc, updated checkstyle config, removed code-formatter, and updated README.md.
Merge pull request #11 from michaeldejong/transactions

Added support for transactions and multi-threading