Contribution widgets break when pasted into ckeditor

The contribution widget code includes at least 2 instances on empty <span> tags which are later filled via javascript. However, these empty span tags are cleaned up by ckeditor. So, for example, if you paste the contribution widget into the introductory text on a contribution, it will fail with a javascript error as getElementById() will return null.

So the easy fix here is to ensure that the automatically generated html widget code includes non-breaking spaces inside empty <spans>.