Create assignment short details widget for submission page

[bogdanciobanu]

The purpose of the widget:

• Show a link to the assignment page with assignment's name
• Show the deadline of the assignment

[bogdanciobanu]

@aismail How can I filter the assignments so I can get only the one the current submission is for? The trick with channel_params doesn't work because we don't have a map between assignments and submissions so I can use this.url_params[0]. I need assignment_id attribute from the current submission, but I don't know where to find it.