Fixes issue where some students couldn't be removed from courses

fixes CNVS-22845

Test Plan:
* Create a user with a sis id, create another user without a sis id
* Add both users to a course with any role
* Once added select the gear icon for both students
* They should both have the option to "Remove From Course"

Change-Id: Ia7c663ae02a1c91334e6d00614faa31c94f1ab40
Reviewed-on: https://gerrit.instructure.com/62151
Tested-by: Jenkins
Reviewed-by: James Williams  <jamesw@instructure.com>
QA-Review: Jahnavi Yetukuri <jyetukuri@instructure.com>
Product-Review: Dan Minkevitch <dan@instructure.com>

app/coffeescripts/views/courses/roster/RosterUserView.coffee

@@ -50,6 +50,7 @@ define [
       json.url = "#{ENV.COURSE_ROOT_URL}/users/#{@model.get('id')}"
       json.isObserver = @model.hasEnrollmentType('ObserverEnrollment')
       json.isPending = @model.pending(@model.currentRole)
+      json.canRemoveStudents = ENV.permissions.manage_students and _.all @model.get('enrollments'), (e) -> !e.sis_course_id
       json.canEditSections = not _.isEmpty @model.sectionEditableEnrollments()
       json.canLinkStudents = json.isObserver && !ENV.course.concluded
       json.canViewLoginIdColumn = ENV.permissions.manage_admin_users or ENV.permissions.manage_students

app/views/jst/courses/roster/rosterUser.handlebars

@@ -49,10 +49,10 @@
       <li><a href="#" data-event="editSections"><i class="icon-edit"></i> {{#t "links.edit_sections"}}Edit Sections{{/t}}</a></li>
       {{/if}}
       <li><a href="{{url}}"><i class="icon-user"></i> {{#t "links.user_details"}}User Details{{/t}}</a></li>
-      {{#unless sis_user_id }}
+      {{#if canRemoveStudents}}
       <li class="ui-menu-item"><hr /></li>
       <li><a href="#" data-event="removeFromCourse"><i class="icon-trash"></i> {{#t "links.remove_from_course"}}Remove From Course{{/t}}</a></li>
-      {{/unless}}
+      {{/if}}
     </ul>
   </div>
   {{/if}}