Merge pull request expressjs#1037 from pbuyle/2.x

Support PURGE request method.

Author: tj

lib/router/methods.js

@@ -54,6 +54,14 @@ var RFC5323 = ['SEARCH'];
 
 var RFC5789 = ['PATCH'];
 
+/**
+ * PURGE Method for caching reverse-proxy
+ * http://wiki.squid-cache.org/SquidFaq/OperatingSquid#How_can_I_purge_an_object_from_my_cache.3F
+ * https://www.varnish-cache.org/docs/trunk/tutorial/purging.html
+ */
+
+var CACHE_PURGE = ['PURGE'];
+
 /**
  * Expose the methods.
  */
@@ -65,6 +73,7 @@ module.exports = [].concat(
   , RFC3648
   , RFC3744
   , RFC5323
-  , RFC5789).map(function(method){
+  , RFC5789
+  , CACHE_PURGE).map(function(method){
     return method.toLowerCase();
   });