Ruby 2.2 support. See rapid7#8792

Author: mpizala

modules/exploits/linux/http/rancher_server.rb

@@ -162,7 +162,7 @@ def exploit
     wait_time = datastore['WAIT_TIMEOUT']
     vprint_status("Waiting up to #{wait_time} seconds until the docker container stops")
 
-    while wait_time.positive?
+    while wait_time > 0
       sleep(sleep_time)
       wait_time -= sleep_time