Use btn-secondary instead of btn-primary. Closes BiscuIT-ng#83.

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

@@ -27,7 +27,7 @@
     {% csrf_token %}
     {% bootstrap_form upload_form %}
 
-    <button type="submit" class="btn btn-primary">
+    <button type="submit" class="btn btn-secondary">
       {% blocktrans %}Process{% endblocktrans %}
     </button>
   </form>