PHP files for server-side storage of todo tasks

@erikthedeveloper, @laklein, @TheValencian 

Here are the PHP files as promised. There were a couple of weird things I had to do to get it all working, but we won't worry about those for now. Feel free to comment away!
Oops...forgot to remove this line. Turns out PHP was storing the true/false value as "true" or "false"...which evaluates to true either way. Non-empty strings are always true.