Decouple SSH forwarding and authentication type

[msbit]

Q	A
Issue Type	Feature Request
Deployer Version	v4.2.1
Local Machine OS	macOS 10.12.3
Remote Machine OS	Ubuntu 16.04.2 LTS

I have a situation where I am deploying to a server that I authenticate with via PEM file, but the repository is accessed via a different SSH key. It would be nice to decouple the authentication method from the forwarding setting, right now calling:

server(...)
  ->pemFile(...)
  ->forwardAgent()

would result in the PEM file being ignored, and:

server(...)
  ->forwardAgent()
  ->pemFile(...)

would result in forwarding not being enabled.

[antonmedv]

Yes, this is known issue with phpseclib. I'm definitely planning to fix it in next Deployer v5 with migration on only native ssh.

[msbit]

@Elfet okay cool

[antonmedv]

Done in #1092