Correctly determine if a task host == localhost

This change is the result of a recent attempt to install Cylc and Rose on a new machine. This particular problem comes up when we have a suite that is configured with a variable remote task host. On the machine, this variable is set to a string that contains the full `host.domain`, which is not being compared correctly as the `localhost`. It then tries to `ssh` to itself to install the suite contact file. (This then fails, because the machine is configured in such a way that it is unable to `ssh` to its own `host.domain` without a password.) This change ensures that the task host string is resolved as `localhost` and will therefore allow the system to skip the complexity of a remote task.