Improve account removal page look

Signed-off-by: Michal Čihař <michal@cihar.com>

weblate/html/accounts/removal.html

@@ -18,7 +18,7 @@
 {% csrf_token %}
 </div>
 <div class="panel-footer">
-<input type="submit" class="btn btn-default" value="{% trans "Delete this account" %}" />
+<button type="submit" class="btn btn-danger"><i class="fa fa-trash"></i> {% trans "Delete this account" %}</button>
 </div>
 </form>
 </div>