Add support for ed25519 ssh key algorithm

[geraldolsribeiro]

This is a new algorithm added to OpenSSH. Support for it in clients is not yet universal. Thus its use in general purpose applications may not yet be advisable.

[geraldolsribeiro]

By overriding the GIT_SSH_COMMAND environment variable in the .env file is possible to use another key instead of the default id_rsa:

GIT_SSH_COMMAND=ssh -i /.microCI_ssh/id_ed25519 -F /dev/null -o UserKnownHostsFile=/.microCI_ssh/known_hosts

[geraldolsribeiro]

Implemented at 9d129b4. Please define an environment variable called MICROCI_DEFAULT_SSH_KEY_NAME with the name of your key at ~/.microCI.env

MICROCI_DEFAULT_SSH_KEY_NAME=id_rsa

or

MICROCI_DEFAULT_SSH_KEY_NAME=id_ed25519