Debug messages for 412 errors

Some users have been running into 412 errors quite a bit, meaning the file was changed since they last saved it. This error is meant to protect against a stale copy being saved to the server, but some users have been reporting 412 errors when they only have one wiki open. This release logs information about the 412 error to the console.

The example-settings-simple.json file contains all the basic options. It also specifies a default tree -- one "data" directory which is sibling to the folder the settings.json file is in.

 - TiddlyServer-2.0.8
    - settings.json
 - data