Support persistent connection, even in single thread mode (i.e concurrency=none).

Warning: as there is no concurrent request handling in single threaded mode,
            it is recommended to either set the keep_alive_timeout to a small value,
            or disable persistent connection by setting max_keep_alive_requests to 0.
Change the default keep_alive_timeout from 15 to 5 seconds.
Accept -1 as value of max_keep_alive_requests to have unlimited number of request in the same persistent connection.

library/server/wsf/connector/standalone/wsf_standalone_service_options.e

@@ -104,11 +104,26 @@ feature -- Access: persistent connection
 			-- Maximum number of requests allowed per persistent connection.
 			-- Recommended a high setting.
 			-- To disable KeepAlive, set `max_keep_alive_requests' to 0.
+			-- To have no limit, set `max_keep_alive_requests' to -1.
 			-- By default: {HTTPD_CONFIGURATION_I}.default_max_keep_alive_requests .	
 		do
 			Result := option_integer_value ("max_keep_alive_requests", 0)
 		end
 
+	persistent_connection_disabled: BOOLEAN
+			-- Persistent connection disabled?
+			-- (or Keep-Alive disabled).
+		do
+			Result := max_keep_alive_requests = 0
+		end
+
+	has_unlimited_keep_alive_requests: BOOLEAN
+			-- Has unlimited count of keep alive requests.
+			-- i.e no limit of number of requests allowed per persistent connection.
+		do
+			Result := max_keep_alive_requests < 0
+		end
+
 feature -- Access: SSL	
 
 	is_secure: BOOLEAN assign set_is_secure
@@ -205,6 +220,16 @@ feature -- Element change
 			set_numeric_option ("max_keep_alive_requests", nb)
 		end
 
+	set_unlimited_keep_alive_requests
+		do
+			set_max_keep_alive_requests (-1)
+		end
+
+	disable_persistent_connection
+		do
+			set_max_keep_alive_requests (0)
+		end
+
 	set_is_secure (b: BOOLEAN)
 			-- Set secured connection enabled to `b'.
 			-- i.e if connection is using SSL/TLS.