GPII-147

Fixes the table of contents links by only looking for headers that exist in the simplified content. I had tried to rerender the ToC after the content was simplified, but couldn't find the correct timing for when to do this. The best I had been able to get with that was to have a the ToC render the original and then updated links. This caused the screen to flicker the ToC content. 

http://issues.gpii.net/browse/GPII-147