BUG 13436 ProcessMaker 2.x Authenticated PHP Code Execution SOLVED

- The function sent in the variable $_REQUEST['action'] was always executed
- A new method was implemented to validate if is a user custom function or a system function (G::isUserFunction)
Merge pull request #2107 from julceslauhub/master

BUG 13436 ProcessMaker 2.x Authenticated PHP Code Execution SOLVED