Small bugfixes and improvements

Collection of improvements to the code. 

Major change (but still small), is the logger. I think all loggers should be on the same level. First, most issues in the tracker have logs copied directly from the log page, and don't include debug information (even if verbose is 1 or 2). Second, even with quiet mode, debug information is written to log file, resulting in large files and a lot of disk access. If one wants to track down an issue, turning on verbose is a lot easier.

With this patch, some Python 2.5 code is removed. If you agree, we could start removing more legacy code (e.g. simplejson, since json is [included](https://docs.python.org/2/library/json.html) in 2.6).