Pull Request:C4_ nadine_421_create assignment_4.27

#421 #598
<h1>Scenario review</h1>
<li>Sign in as TA/Lecturer</li>
<li>Click on courses</li>
<li>click on create assignment</li>
<li>create assignment,then click on save</li>
<li>create problem or copy from existing problems</li>