Changed action to use sub item for configuration.

Action originally used the action.group.item configuration for the
action being executed.  To update for the change to Config::path, which
would allow action.group.item.path to point explicitly to an item or for
action.group.path to point to the directory of actions, the action
configuration is being moved to the used action.group.item.config
Changed string joins.
Added Template class to simple PHP-style templates
Added more tests to Template.

New tests were added to check for correct handling if an exception is
thrown in a template. Handling should still revert the saved template
paramaters state and end the current level of buffering in the template.