SFTP Operator enhancements

[phanig]

• Airflow Plugins version: 1.0
• Python version: 2.7
• Operating System: MacOS high Sierra

Description

While Airflow's SFTP Operator is great, we at Freedom Financial's had implemented new features like

1. Ability to get list of files on SFTP site.
2. Ability to get filtered list of files on SFTP site by passing parameters like path and delimiter.
3. Ability to create/delete directories on SFTP site.

What I Did

We would like to contribute back to the community.

[VojtechBartos]

Hi @phanig, these features would be nice to have as well, so if you have already implemented it, feel free to create a new PR. We would really appreciate it :)