support ed25519 ssh key format

[stefreak]

Issue and Steps to Reproduce

I want to work remotely on a server that only allows connections via ed25519.

Expected Behavior

Authentication via ed25519 private / public keypair incl. certificates should work.

Actual Behavior

SSH-Agent: Nuclide asks for password.
Private key file: Cannot parse privateKey: Unsupported key format

Versions

• Atom: 1.15.0
• Nuclide: 0.211.0
• Client OS: Mac OS 10.11.6
• Server OS (optional): Ubuntu 16.04 Xenial

Additional Details

• Installed packages (apm ls --installed):

Community Packages (1) /Users/stefreak/.atom/packages
└── [email protected]

[aadisriram]

You should convince this to happen mscdex/ssh2#352 :)
We use the external ssh library

[stefreak]

@aadisriram thanks, I poked them.