Add FTPS support

[jgoldverg]

The current FTP Reader and Writer do not support FTPS I believe. There should be some configurable way to make the FTPClient use ssl.

I would read through the javadocs to check if there is some easy flag.

The set up: When an endpoint type of ftp is used for source or destination then we use the FTP Reader or Writer(or both). Now if the flag in transfer-options(encrypt) is set to true then we want to use FTPS and not the base FTP protocol. The FTPClient class should support FTPS if a flag is passed in.
This can be done in the FTPConnectionPool where we create clients so that the readers and writers do not have to change.