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!
I would opt for an `if/else` here rather than pushing all of the tasks.index and tasks.create logic into a switch case. I feel like it would accommodate growth/complexity better.

Something like `if ($method == "POST") {...}` and so on.