[OFFAPPS-121] Restore drag and drop for article title

:bug:

Restore drag and drop for article title.

JIRA: https://zendesk.atlassian.net/browse/OFFAPPS-106

![demo](https://f.cloud.github.com/assets/172804/1279858/e7b83880-2f42-11e3-8450-a088484c74aa.gif)

/cc @maximeprades