Permissions cascade

Hi Boone-

Here's a small addition to the js that updates the edit/read comments/post comments/etc permissions based on the level selected for the read setting. The only commit that is of interest is https://github.com/dcavins/buddypress-docs/commit/f6dadcb9d68f7864f89a8208d0ac58253673418c

-David

Update==

This is a great idea if the user works from top to bottom but fails if the user bounces around and set something farther down then returns to the read setting. I think the jQuery will have to compare values and only update less-restrictive values, but leave the more restrictive values alone.