Added Update-mcedit filter

This fixes mcedit Issue [443](https://github.com/mcedit/mcedit/issues/443)

This does require the user to be an administrator to update mcedit. The file that manages the latest mcedit version urls and names is hosted on Drop-box and downloaded everytime the filter runs, the filter uses the urls from the mcedit site. The filter, however, needs a mac script to be added to close the mcedit.exe window, and copy all the files from the "temp" directory.

[Url File](http://dl.dropboxusercontent.com/s/uqyglkcjg3wmsk8/urls.txt)