fix calamari-ctl initialize error "TEMPLATE_DIRS setting must be a tuple"

When setting calamari according to "http://calamari.readthedocs.org/en/latest/development/dev_env.html", by executing "CALAMARI_CONFIG=dev/calamari.conf calamari-ctl initialize", error happens.
Log in /tmp shows: "ImproperlyConfigured: The TEMPLATE_DIRS setting must be a tuple. Please fix your settings.".
Cause: TEMPLATE_DIRS here in settings.py is one element tuple which should have a comma.
Environment: Python 2.7.6, Ubuntu Trusty.

Signed-off-by: Xan Peng xanpeng@gmail.com

Closes #196