Allows an integer to be hashed, and decoded back.
Original class created by Ray Morgan
http://raymorgan.net/web-development/how-to-obfuscate-integer-ids/
$hash = IdObfuscator::encode(1234); //returns cRDtpNCeBirJZY$IuwhXSQ $id = IdObfuscator::decode($hash) //return 1234