Check for hosts in nextsubnet. Fixes #23

[kd7lxl]

Demo:

(env)tom@Baldi-SRV1:~/src/hamwanadmin$ ./manage.py nextsubnet point-to-point 30
https://encrypted.hamwan.org/admin/portal/subnet/add/?network=44.25.8.16/30
44.25.8.16/30

(env)tom@Baldi-SRV1:~/src/hamwanadmin$ ./manage.py nextsubnet point-to-point 30 --ignore-hosts
https://encrypted.hamwan.org/admin/portal/subnet/add/?network=44.25.8.0/30
44.25.8.0/30

(env)tom@Baldi-SRV1:~/src/hamwanadmin$ ./manage.py nextsubnet --help
Usage: ./manage.py nextsubnet [options] <block name> <prefix length>

Prints the next available subnet in the specified block.

Suggested block names:
    New space
    End-user DHCP and direct allocations
    Infrastructure
    Loopback
    Anycast
    OPP
    Point-to-Point
    HamWAN Open Peering Policy client gateway addresses
    Loopback interfaces
    Anycast
Block names use case-insensitive starts-with matching.

Options:
  -v VERBOSITY, --verbosity=VERBOSITY
                        Verbosity level; 0=minimal output, 1=normal output,
                        2=verbose output, 3=very verbose output
  --settings=SETTINGS   The Python path to a settings module, e.g.
                        "myproject.settings.main". If this isn't provided, the
                        DJANGO_SETTINGS_MODULE environment variable will be
                        used.
  --pythonpath=PYTHONPATH
                        A directory to add to the Python path, e.g.
                        "/home/djangoprojects/myproject".
  --traceback           Raise on exception
  --ignore-hosts        Skips checking for any hosts in the new subnet
  --version             show program's version number and exit
  -h, --help            show this help message and exit

[turnrye]

@kd7lxl I know via e-mail you mentioned wanting to see CI running the tests, but it looks like 3 months ago you already added this. So congrats, future you, because past you helped you out!

[dpkingston]

LGTM. And we have been running on this for some time without issue. This is a post push approval in large part to clean up the pull request backlog.