increase specific input label widths in templates

In the registration template, both the “Terms of Use” and “Remember Me” checkbox labels were subject to the universal `.affwp-form label` width of 200px. That’s cool when the labels are to the left of a text input field but made bad use of open space (to the right) for label text that has nothing but a checkbox to the left. [screenshot](http://glui.me/?i=9hbrin2qzkcjzbl/2014-05-05_at_1.00_AM.png/)

There was no markup in place to target these labels so I added the classes. I combined the two new CSS selectors with the selector for a label located in the dashboard template that has already addressed this exact issue (referral notifications checkbox label).