Update ftpkick with implemented checkfile

I've updated the `ftpkick` package to implement a "checkfile", that saves the modification time for all uploaded files. Then it locally checks if the files in `build/` or whatever directory is newer than the one listed in the checkfile.

The checkfile is saved in the OS' temp dir, and the name of file can be altered (although this is unnecessary) with the environment variable `LYT_FTP_CHECKFILE`

This quickens up the `cake deploy` task *A LOT* except for the first upload (where the checkfile hasn't been generated). It now takes less than a second on my machine.

This hasn't been tested on Windows, nor Linux, so if anyone would like to give it a try, please do before merging this.