add log poisonings

[klaxon1]

to resolve issue: #14

• new command line argument --log-poisonings POISIONINGSLOG

$ dnsvalidator -h
usage: dnsvalidator [-h] [-t TARGET | -tL TARGET_LIST]
                    [-e EXCLUSION | -eL EXCLUSIONS_LIST] [-o OUTPUT]
                    [-r ROOTDOMAIN] [-q QUERY] [-threads THREADS]
                    [-timeout TIMEOUT] [--no-color] [-v | --silent]
                    [--log-poisonings POISONINGSLOG]

optional arguments:
  -h, --help            show this help message and exit
  -t TARGET             Specify a target DNS server to try resolving.
  -tL TARGET_LIST       Specify a list of target DNS servers to try to
                        resolve. May be a file, or URL to listing
  -e EXCLUSION          Specify an exclusion to remove from any target lists.
  -eL EXCLUSIONS_LIST   Specify a list of exclusions to avoid resolving. May
                        be a file or URL to listing
  -o OUTPUT, --output OUTPUT
                        Destination file to write successful DNS validations
                        to.
  -r ROOTDOMAIN         Specify a root domain to compare to (default:
  -q QUERY              Specify a resolver query to use (default:dnsvalidator)
  -threads THREADS      Specify the maximum number of threads to run
                        (DEFAULT:5)
  -timeout TIMEOUT      Command timeout in seconds (DEFAULT:600)
  --no-color            If set then any foreground or background colours will
                        be stripped out.
  -v, --verbose         If set then verbose output will be displayed in the
                        terminal.
  --silent              If set only findings will be displayed and banners and
                        other information will be redacted.
  --log-poisonings POISONINGSLOG
                        Destination file to write detected poisoned DNS
                        servers to.

• with new argument

$ dnsvalidator --log-poisonings test.txt
=======================================================
dnsvalidator v0.1	by James McLean (@vortexau) 
                	& Michael Skelton (@codingo_)
=======================================================
[22:00:40] [INFO] [1.1.1.1] resolving baseline
[22:00:40] [INFO] [8.8.8.8] resolving baseline
[22:00:40] [INFO] [9.9.9.9] resolving baseline
[22:00:41] [INFO] [109.86.225.220] Checking...
...
[22:01:24] [ACCEPTED] [156.154.70.40] provided valid response
[22:01:24] [INFO] [208.93.4.81] Checking...
[22:01:24] [ERROR] [208.93.4.81] DNS poisoning detected, logging target to test.txt
[22:01:24] [INFO] [190.56.169.145] Checking...

$ cat test.txt 
208.93.4.81

• without new argument

$ dnsvalidator
=======================================================
dnsvalidator v0.1	by James McLean (@vortexau) 
                	& Michael Skelton (@codingo_)
=======================================================
[22:04:56] [INFO] [1.1.1.1] resolving baseline
[22:04:57] [INFO] [8.8.8.8] resolving baseline
[22:04:57] [INFO] [9.9.9.9] resolving baseline
[22:04:57] [INFO] [193.36.189.34] Checking...
...
22:07:17] [INFO] [89.216.29.90] Checking...
[22:07:18] [ACCEPTED] [210.57.211.36] provided valid response
[22:07:18] [INFO] [82.99.211.195] Checking...
[22:07:19] [ERROR] [82.99.211.195] DNS poisoning detected, passing
[22:07:19] [INFO] [148.240.167.69] Checking...

[codingo]

Don't have a chance to look at this currently, but before merging this should also be tested with --silent (should be suppressed).