Convert Admin Settings to DNN 6 form pattern

Replace CollapsiblePanelExtender with dnnPanels
Convert tables to fieldsets
Convert table rows to div.dnnFormItem
CSS cleanup
Remove unused CSS
Clean up saving settings
Add CAPTCHA settings to admin settings
Add configuration of CAPTCHAs to Email a Friend
Enable/disable CAPTCHA for email a friend based on settings
Add CAPTCHA to comments
Merge pull request #10 from bdukes/captcha-setting

CAPTCHA settings
Merge pull request #11 from bdukes/css-cleanup

CSS Cleanup