Make ssh login user configurable

[berendt]

At the moment the ubuntu user is hard coded (ansible_ssh_user, ansible_ssh_common_args). The login user should be configurable.

[ctrlaltdel]

Hi @berendt,

I have mixed feelings on this one, making the username configurable would probably deviate from the "opiniated way" from the project description :)

Could you perhaps elaborate a bit more on why you would need this feature? Thanks!

[berendt]

@ctrlaltdel I want to use a self build Ubuntu image. There the initial login name is not ubuntu.