This set of updates fix several issues related to the JEB backend:

1. The db directory is now automatically created if it doesn't alreadly exist. When changing the db directory, a message is now displayed to let the user know the files will have to be manually moved and the backend restarted. (Issue 1979)

2. The backend no longer uses the Database.count method in JE as it is too expensive for large databases. The count can also be inaccurate when concurrent operations are executing on the server. This was causing the getEntryCount method up to 20 seconds to return. The count is now obtained from the id2subtree index. If the count is not maintained or the index is corrupt, it will fall back to using Database.count. (Issue 2581 and Issue 2420)