Remove FTP support from the core of the Filesystem\File and Filesystem\Folder classes.

This also removes the ClientHelper class and tests as well as the ClientHelper references
from Factory. This brings us one more step closer to dropping Factory as well.

Finally, this moves FtpClient out of the Client package and into Filesystem\Clients\FtpClient.
If you need FTP support, use it directly, instead of through the File / Folder classes.
remove joomla/client from composer.json
help tests to stand alone
fix failing tests due to misplaced .gitkeep
Define JPATH_ROOT for the Patcher tests
Merge pull request #230 from dongilbert/cleanup-Filesystem

Remove FTP support from Filesystem\File and Filesystem\Folder