edx/edx-platform — pull request #1891 by polesye (2013-12-09 15:17:44+00:00)
Title: Anton/fix lti dnd

This PR adds fix for [BLD-543](https://edx-wiki.atlassian.net/browse/BLD-543).

LTI module is refactored in this PR.

@valera-rozuvan , @auraz please review.