Support the option "--password-file"

[koolay]

This plugin is great, it works well with ssh key.
Will plan to support the option --password-file ?

[mjwwit]

Using --password-file is not recommended as your files will be transferred unencrypted. Knowing this, is it still something you want?

[koolay]

In my case, it is still a optional.

[mjwwit]

In that case, I may add it when I get around to it. If you're in a hurry, feel free to submit a PR.