Merge branch 'core-issue-81' into 'master'

Use bootstrap buttons. Advances BiscuIT-ng#81.

See merge request Teckids/BiscuIT/BiscuIT-App-Untis!6

biscuit/apps/untis/templates/untis/untis_import.html

@@ -27,6 +27,8 @@
     {% csrf_token %}
     {% bootstrap_form upload_form %}
 
-    <input type="submit" value="Process" />
+    <button type="submit" class="btn btn-primary">
+      {% blocktrans %}Process{% endblocktrans %}
+    </button>
   </form>
 {% endblock %}