This change makes a distinction between no_hosts_matched and no_hosts_remaining.

In both cases we do not start facts-gathering, or run any tasks.

In the case that there are no more hosts remaining, we abort running tasks and abort the playbook.

I also cleaned up the leftovers from the previous patchsets, as these are no longer required.

This closes #1187.

Example playbook:

```yaml
---
- hosts: emptygroup
  tasks:
  - action: command date
  - action: command false

- hosts: all
  gather_facts: False
  tasks:
  - action: command ls
  - action: command false
  - action: command true

- hosts: all
  tasks:
  - action: command true
  - action: command false

- hosts: all
  tasks:
  - action: command pwd
```