Better welcome message

frontend/src/components/WelcomeJumbotron.vue

@@ -3,7 +3,7 @@
       <v-container fill-height>
         <v-layout align-center>
           <v-flex>
-            <h1 class="display-2 mb-2">Welcome to the Grady correction software</h1>
+            <h1 class="display-2 mb-2 text-xs-center">Grady</h1>
             <span class="subheading">
               The intention of this tool is to simplify the exam correcting process at the
               University of Goettingen. It is deployed as a