Wrap everything top-level in a paragraph

Summary:
Monkey patch ALL the things!

We weren't wrapping tables in div class="paragraph", so they were missing padding to
separate them from other things (especially tables at the end of the questionarea
running into hints).
We also weren't wrapping non-paragraphs in QuestionParagraph elements to get orange
"has been answered" indicators. This fixes that too.

This commit is a total hack that fixes those problems by monkey-patching marked-react
(sorry!).

Test Plan:
Enable `shouldIndicate` in src/item-renderer.jsx (we should make this enabled in test.html by default)
visit:
http://localhost:9000/test.html#content=%7B%22question%22%3A%7B%22content%22%3A%22%5Cnheader%201%20%7C%20header%202%20%7C%20header%203%5Cn-%20%7C%20-%20%7C%20-%5Cndata%201%20%7C%20data%202%20%7C%20data%203%5Cndata%204%20%7C%20*bold*%20%7C%20data%206%5Cndata%207%20%7C%20data%208%20%7C%20data%209%5B%5B%E2%98%83%20input-number%201%5D%5D%5Cn%5Cn%5B%5B%E2%98%83%20input-number%202%5D%5D%22%2C%22widgets%22%3A%7B%22input-number%201%22%3A%7B%22type%22%3A%22input-number%22%2C%22graded%22%3Atrue%2C%22options%22%3A%7B%22value%22%3A%220%22%2C%22simplify%22%3A%22required%22%2C%22size%22%3A%22normal%22%2C%22inexact%22%3Afalse%2C%22maxError%22%3A0.1%2C%22answerType%22%3A%22number%22%7D%7D%2C%22input-number%202%22%3A%7B%22type%22%3A%22input-number%22%2C%22graded%22%3Atrue%2C%22options%22%3A%7B%22value%22%3A%220%22%2C%22simplify%22%3A%22required%22%2C%22size%22%3A%22normal%22%2C%22inexact%22%3Afalse%2C%22maxError%22%3A0.1%2C%22answerType%22%3A%22number%22%7D%7D%7D%7D%2C%22answerArea%22%3A%7B%22type%22%3A%22multiple%22%2C%22options%22%3A%7B%22content%22%3A%22%22%2C%22widgets%22%3A%7B%7D%7D%2C%22calculator%22%3Afalse%7D%2C%22hints%22%3A%5B%5D%7D
look at the lovely orange marker for the table, and note that the table is wrapped in a <div class="paragraph">

Reviewers: justinjaffray

Reviewed By: justinjaffray

Subscribers: alpert, alex

Differential Revision: http://phabricator.khanacademy.org/D7749