Land rapid7#5100, @bcook-r7's deletekey API usage fix

Fixes rapid7#5099

Author: zeroSteiner

lib/rex/post/meterpreter/extensions/stdapi/sys/registry_subsystem/registry_key.rb

@@ -163,7 +163,11 @@ def delete_value(name)
   # Returns the path to the key.
   #
   def to_s
-    return self.root_key.to_s + "\\" + self.base_key
+    if self.base_key.nil?
+      self.root_key.to_s + "\\"
+    else
+      self.root_key.to_s + "\\" + self.base_key
+    end
   end
 
   #

lib/rex/post/meterpreter/ui/console/command_dispatcher/stdapi/sys.rb

@@ -641,11 +641,11 @@ def cmd_reg(*args)
         when "deletekey"
           open_key = nil
           if not rem
-            open_key = client.sys.registry.open_key(root_key, base_key, KEY_WRITE + wowflag)
+            open_key = client.sys.registry.open_key(root_key, nil, KEY_WRITE + wowflag)
           else
             remote_key = client.sys.registry.open_remote_key(rem, root_key)
             if remote_key
-              open_key = remote_key.open_key(base_key, KEY_WRITE + wowflag)
+              open_key = remote_key.open_key(nil, KEY_WRITE + wowflag)
             end
           end
           open_key.delete_key(base_key)