safe_encode() method is not defined

[Wiktor Walc]

In curlit() function, there is a method called that does not exist: safe_encode()

https://github.com/XeroAPI/XeroOAuth-PHP/blob/0d2578/lib/XeroOAuth.php#L212

[Ronan Quirke]

Sloppy re-write from me! Thanks, now reinstated and used to handle encoding.