Fix undefined index error in sidebar testimonial widget.

Add two new classes, one to Author and one to Position, for additional styling control over the output.

Add support for Captcha, using the Really Simple Captcha plugin, to the front end testimonial form.

git-svn-id: https://plugins.svn.wordpress.org/easy-testimonials/trunk@918087 b8457f37-d9ea-0310-8a92-e5e31aec5664