remove linebreaks import from web certs

lms/templates/certificates/_accomplishment-rendering.html

@@ -1,5 +1,4 @@
 <%! from django.utils.translation import ugettext as _ %>
-<%! from django.template.defaultfilters import linebreaks %>
 <%namespace name='static' file='../static_content.html'/>
 <%
 course_mode_class = course_mode if course_mode else ''