Radio button not always clickable + make payment option entirely clickable

- Fixes radio input not being clickable all the time. Sometimes it takes 3-5 clicks to register
- Swapped <span>'s for <label>'s and add "for" attribute so each payment option is entirely clickable
Merge pull request #952 from sumobi/master

Radio button not always clickable + make payment option entirely clickable
Simplified removal of PayPal CC form
Added new headers to PayPal post back for HTTP 1.1. Closes #930
Add (optional) to billing line 2. #949