Fix settings for Django 1.6

The new version was unhappy about the fact that TEMPLATE_DIRS was not a
tuple. This change *should* be safe for Django 1.5.
Move PLC IP configuration to the settings file

The IP address of the PLC is configuration, so it belongs in the
settings.py file.
Moreover, we'll want to re-use parts of this code for other features
(outside of the webapp), so it doesn't make sense to keep that
information in the views file (very much webapp only).
Kill a debug print