fix: bogus messages when template didn't exist.

Refactored out the common code and corrected the bad error message.
chg: dev: more output intelligence moved towards templates !refactor
new: dev: added a new test to run at least once all provided templates.
new: added 'octobercms-plugin' mako template. (fixes #16)
new: provide support for older config file format.
new: dev: added a ``body`` and an sole ``Other`` section to reference tests.