Adds RaceConditionIT for issue 349 and makes the number of io threads configurable
Synchronizes MongoDocument.putAll in an attempt to fix concurrency issues
Reformats all touched files in PR
Removes assertion which tests nothing
Sets race condition tests to ignore. The test can reproduce the issue sometimes, but is too unstable to run on build servers. Needs to be revisited
Merge pull request #351 from Nycander/349-race-condition

Add configurable number of IO dispatchers and synchronize on MongoDocument.putAll