Partially implement 'user responds with input box'

Implement first 3 AC for 'user responds with input box' US.
Implement correct answer checks on SolutionString and Card models.
Implement correct answer detection

Implement 'User sees that their answer is correct/incorrect'.
Bump Ruby version. Use forked guard/rspec to get around rspec
version limitation in official source. Implement CardSubmissionLog
controller.
[#51488383]
Implement 'User responds to card with input box'

Implement all AC for 'User responds to challenge card with an input
box' US.
[Finishes #51488383]