Add SFTP connector support #26
Description
Create a dedicated set of connectors for working with SFTP uploads/downloads
Building off of #24 and #25 we could develop a generalized set of connectors that other convenience functionality could dispatch to i.e. the SA360 SFTP connectors would hardcode to the SA360 partner upload host:port endpoint out of convenience and code explicitness and just dispatch to the more generalized SFTP connector