Added external url option. Untested branch.
Changed pie_name in api from demo to the pie's actual name.
Added get_slide_location. Lack of central helper function file means this function is duplicated in the code. We need to consolidate functionality into fewer plugins.
Added external url section to meta box for slide creation.
Changed single-slide.php to iframe external urls where necessary.
Duplicate function not needed. That's how wordpress works.
Merge remote-tracking branch 'origin/external-url' into external-url

Conflicts:
	wp-content/themes/twentyfourteen/single-slide.php
Added line breaks to DDS meta box.
Merge pull request #1 from crew/external-url

Feature: PIEs directly loading external urls as slides