Remove redundant loading of variables.css

variables.css doesn't need to be loaded by any template, since
WHOOGLE_CONFIG_STYLE loads those values by default when not set
explicitly. Loading the stylesheet caused the logo colors to be
persistent unless set individually.

Sorry @gripped for sneaking all of this unnecessary color in...

Fixes #492

app/templates/display.html

@@ -7,7 +7,6 @@
         <meta name="referrer" content="no-referrer">
         <link rel="stylesheet" href="{{ cb_url('input.css') }}">
         <link rel="stylesheet" href="{{ cb_url('search.css') }}">
-        <link rel="stylesheet" href="{{ cb_url('variables.css') }}">
         <link rel="stylesheet" href="{{ cb_url('header.css') }}">
         {% if config.theme  %}
             {% if config.theme == 'system' %}

app/templates/index.html

@@ -21,7 +21,6 @@
         <script type="text/javascript" src="{{ cb_url('controller.js') }}"></script>
 		<link rel="search" href="opensearch.xml" type="application/opensearchdescription+xml" title="Whoogle Search">
 		<meta name="viewport" content="width=device-width, initial-scale=1.0">
-        <link rel="stylesheet" href="{{ cb_url('variables.css') }}">
         {% if config.theme  %}
             {% if config.theme == 'system' %}
             <style>