Improve candidate validation logic

lib/request-analyzer.js

@@ -73,6 +73,12 @@ exports.isValidCandidate = function (httpChannel) {
 
     var initiatorDomain;
 
+    // See if the request uses a supported URI scheme.
+    if (!httpChannel.URI.schemeIs('http') &&
+        !httpChannel.URI.schemeIs('https')) {
+        return false;
+    }
+
     // See if the request is targeted at a Content Delivery Network.
     if (mappings[httpChannel.URI.host] === undefined) {
         return false;