For SAT, hide radio buttons entirely and draw buttons in css, to work on FF & IE.

Test Plan:
Load up /mission/sat on FF & IE (haven't actually tested IE yet).

Auditors: dylan, johnsullivan
Turn SAT input field blue once it contains an answer.
Not seeing the current Review mode coloring, so I'm not sure how this will interact with that. Where did that code go?

Test Plan:
Works in conjunction with "required" injection in webapp; the input is :valid when it is not empty

Reviewers: dylan, johnsullivan
Cc: aria