Update and simplify main script.

* Use argparse instead of optparse.
* Change minimum required version from python 2.4 to python 2.7.
* Support only a single configuration file.
* Start only a single phenny instance.
Update default configuration file.
Update main script's file header.
Update phenny module's __init__.py.

* Update file header.
* Use default value if "delay" given in config is not an integer.
* Drop multiple bot support.