prevent cloning duplicate extensions (master #1821) (#2033)

* prevent cloning duplicate extensions

app/extensions/app_languages.php
+ add duplicate extension error prompt

app/extensions/extension_copy.php
+ add check to see if duplicate extension exists

app/extensions/resources/classes/extension.php
+ add function to check if extension exists

* fix typo

* Update app_languages.php

* Update extension_copy.php

* Update extension.php

* Update extension_copy.php

Use the global app_languages.php message-duplicate translation.

* Update extension_copy.php

* Update extension.php

app/extensions/resources/classes/extension.php

@@ -17,7 +17,7 @@
 
 	The Initial Developer of the Original Code is
 	Mark J Crane <markjcrane@fusionpbx.com>
-	Copyright (C) 2010 - 2014
+	Copyright (C) 2010 - 2016
 	All Rights Reserved.
 
 	Contributor(s):
@@ -518,6 +518,18 @@ if (!class_exists('extension')) {
 					$_SESSION["reload_xml"] = true;
 			}
 		}
+
+		// returns true if the domain extension already exists
+		public function exists($domain_uuid, $extension) {
+			$sql = "select * from v_extensions where domain_uuid = '".$domain_uuid."' ";
+			$sql .= "and extension='".$extension."'";
+			
+			$prep_statement = $this->db->prepare(check_sql($sql));
+			$prep_statement->execute();
+			$result = $prep_statement->fetchAll(PDO::FETCH_NAMED);
+			
+			return count($result) != 0;
+		}
 	}
 }