templates/index: Directly referencing config.REFRESH_RATE

Fixes https://github.com/voxpupuli/puppetboard/issues/213

Also changing the 'if' condition from '!=' to '>' since this application
can only work with unsigned integers

puppetboard/templates/index.html

@@ -1,8 +1,8 @@
 {% extends 'layout.html' %}
 {% import '_macros.html' as macros %}
 {% block content %}
-{% if refreshrate != 0 %}
-<meta http-equiv="refresh" content="{{refreshrate}}">
+{% if config.REFRESH_RATE > 0 %}
+<meta http-equiv="refresh" content="{{config.REFRESH_RATE}}">
 {% endif %}
 <div class="ui vertical grid">
   <div class="four column row">