Show smiley and any messages when checking answer

Summary:
Brian said it was annoying to debug messages before, hopefully this
makes that a bit easier.

Also a bit more obvious how to test getting answers.

Test Plan:
* Open perseus, answer a question correctly
* Click the check answer button, should get the smiley face
* Add an input-number
* Insert something that will not parse ("dsf,fd--fds%%$@" works)
* check answer, should see the message.

* Subperseus
* the above should still work

Reviewers: jack, brianmerlob

Reviewed By: brianmerlob

Differential Revision: http://phabricator.khanacademy.org/D8289