patterns should never be cached

Author: dmolsen

source/_patternlab-files/pattern-header-footer/header.html

@@ -4,6 +4,13 @@
 	<title>Pattern Lab Pattern</title>
 	<meta charset="UTF-8">
 	<meta name="viewport" content="width=device-width" />
+	
+	<!-- never cache patterns -->
+	<meta http-equiv="cache-control" content="max-age=0" />
+	<meta http-equiv="cache-control" content="no-cache" />
+	<meta http-equiv="expires" content="0" />
+	<meta http-equiv="expires" content="Tue, 01 Jan 1980 1:00:00 GMT" />
+	<meta http-equiv="pragma" content="no-cache" />
 
 	<!--
 		Styleguide CSS is included for