Student submissions are sorted by name on StudentPage

Also, the student is not greeted with the anonimised name anymore

fixes #131

frontend/src/components/student/SubmissionList.vue

@@ -33,7 +33,7 @@ export default {
           text: 'Task',
           align: 'left',
           value: 'type.name',
-          sortable: false
+          sortable: true
         },
         {
           text: 'Score',

frontend/src/pages/student/StudentPage.vue

@@ -3,7 +3,7 @@
       <v-layout justify center>
         <template v-if="loaded">
           <v-flex md10 mt-5 offset-xs1>
-            <h2>Submissions of {{ studentName || 'Student'}}</h2>
+            <h2>Your submissions:</h2>
             <submission-list :submissions="submissions"/>
           </v-flex>
         </template>
@@ -28,7 +28,6 @@ export default {
     }
   },
   computed: {
-    studentName () { return StudentPage.state.studentName },
     submissions () { return StudentPage.state.submissionsForList },
     loaded () { return StudentPage.state.loaded }
   }