Enable blocks to be embedded in hints.  This needs cleanup.
Made iframe transparent, per Brian's suggestion.
Removed testing code from maze.js.
Added comment. Replaced trimRight() with trim() for IE9.
Merge branch 'master' into hints
Minor style changes.
Improved comment.
Improved comment per Nan's suggestion.
Merge pull request #661 from code-dot-org/hints

Added ability to embed blocks in hints provided through dashboard