Adds ability to output banners with image as an image tag, not just as a background image.

Adds link to CSS documentation on website.

Adds link to general documentation on website.

Repositions menu item below Comments, to avoid running out of space and the item dissappearing.

git-svn-id: https://plugins.svn.wordpress.org/custom-banners/trunk@866402 b8457f37-d9ea-0310-8a92-e5e31aec5664