Add srvport to HttpServer

This allows URIPORT to override SRVPORT.

lib/msf/core/exploit/http/server.rb

@@ -490,6 +490,19 @@ module Exploit::Remote::HttpServer
     host
   end
 
+  #
+  # Returns the local port that is being listened on.
+  #
+  def srvport
+    if datastore['URIPORT']
+      port = datastore['URIPORT']
+    else
+      port = datastore['SRVPORT']
+    end
+
+    port
+  end
+
   #
   # Removes a URI resource.
   #