* Add exclude option to nmap device tracker
Adds an optional exclude paramater to nmap device tracker.
Devices specified in the exclude list will never be scanned
by nmap. This can help to reduce log spam.
ex:
```
device_tracker:
- platform: nmap_tracker
hosts: 10.0.0.1/24
home_interval: 1
interval_seconds: 12
consider_home: 120
track_new_devices: yes
exclude:
- 10.0.0.2
- 10.0.0.1
```
* Handle optional exclude
* Style fixed