Add tests for no STDIN but --password-from-stdin option is provided

[h-artzi]

Both conjurctl account create and conjurctl server accept the switch --password-from-stdin. Please add tests that address the scenario that no STDIN is provided but the user provides this option.

The tests would look something like this:

it "no STDIN but `--password-from-stdin` option is present" do
      system("conjurctl account create --name demo --password-from-stdin")
      # Attempt to catch stderr output: `Please provide an input via STDIN`
      expect(Slosilo["authn:demo"]).not_to be
      expect(Role["demo:user:admin"]).not_to be
end

Errors I ran into:

• output("Please provide an input via STDIN").to_stderr_from_any_process errored out on can't convert Tempfile into StringIO
• Without attempting to catch the output the command would just hang waiting for STDIN input (in Jenkins), but pass locally.
  I did not attempt to write a cucumber test, but that might be an option to consider as well.