edx/edx-platform — pull request #1698 by polesye (2013-11-18 20:15:44+00:00)
Title: Allow multiple answers for string response.

This PR provides functionality that allows multiple strings as the correct answer to a string response question.
For more information see [BLD-474](https://edx-wiki.atlassian.net/browse/BLD-474).

@auraz, @valera-rozuvan, @Lyla-Fischer please review.