Allow logging page access times.

If settings.LOGGING_PAGE_TIMES is set to True, page access times (along with HTTP method, URL, and user) are logged. This can be handy in tracking performance problems and blocked page loads.

Added a controlled_subprocess context manager for Python 2.5+.

This is useful for using subprocess.Popen() on a process that may end up blocking. It ensures that a blocked process will terminate.

This is experimental and may change in behavior, or move to a new file.

Patch by Mike Conley.