Accept ECDSA keys in keys:add

[public]

Fixes #1262

[deis-bot]

Thanks for the contribution! Please ensure your commits follow our style guide. This code will be tested once a Deis maintainer reviews it.

[public]

Not sure how I should test this. test_keys.py doesn't seem to setup the SSH keys it uses in the tests and just hopes that whatever is ~/.ssh is right?

[bacongobbler]

You could add server-side tests that ensure RSA and ECDSA keys are accepted and invalid keys are refused. Sadly the client tests have been left unloved for a while, but we're interested in resurrecting them when we re-write the client in Go :)

[public]

@bacongobbler Added some ECDSA tests.

[carmstrong]

👍 Code LGTM!

[mboersma]

@public, could you amend your commit messages for our style guide please? Something like feat(controller): accept ECDSA keys in keys:add.

Code LGTM. Thanks very much!

[public]

I guess not then :-)