FIX for issue 938, added remark request count on dashboard

Added a message to the dashboard that indicates the number of outstanding remark requests for each assignment. The message is not shown if there isn't any request. The message links to the assignment submissions page, sorted by marking state.

French translations for the messages are needed.

![Screenshot from 2013-02-20 09:33:59](https://f.cloud.github.com/assets/993257/178659/5147e602-7bc4-11e2-90d5-532f0b6bffb3.png)