Added the possibility to block iPhone 5/4S/iPad3

This changes allow a real private server. If the parameter "private_to_all_devices" in the config.yml is set to "ON", Siri-native devices have to be unlocked in the database just like iPhone 4/3GS. If this parameter is 'OFF' or something other than 'ON', there is no difference to the previous version of siriproxy.
Please also accept the change of the config.yml
Merge pull request #401 from Raggyx/patch-1

Added the possibility to block iPhone 5/4S/iPad3