Continue logging if log rotation fails.

We discovered that if the user executing a jPOS applications runs out of file handles then jPOS stops logging the next time the log tries to roll. It's a bit of a disaster scenario, but it's the kind of scenario where continuing to log is really really useful.

I've changed logRotate() in DailyLogListener and RotateLogListener so that they try to create a new file *before* closing the current one, and to continue logging to the current file if rotation fails.

**I haven't tested this on Windows at all.** (Would have tried, but I don't have a Windows dev setup.)

I'm pretty sure the tests won't work because I simulate the 'out of file handles' condition by making the parent directory of the log files not-executable, which stops Linux changing the directory file. So I think someone will need to provide a Windows-based implementation of preventNewFileCreation() and allowNewFileCreation() in LogRotationTestDirectory and switch based on some System property that reveals the platform.

The implementation *may* work on Windows or may not - it depends on the ability of the OS to continue appending to an open file handle even after the file has been renamed. Not sure if Windows supports this or not. I imagine it could also cause issues if anyone is writing their log files to a location that's not local storage.