Log Message:
Update mail/py-spf to 2.0.12, and switch to net/py-pydns (the previous
dependency on net/py-dns was incorrect and cannot have worked).

Changes since 2.0.8:

Version 2.0.12 - August 5, 2015
  * Reset void_lookups at top of check()
  * Ignore permerror for best_guess()
  * Don't crash on null DNS TXT record (ignore): test case null-text
  * Trailing spaces are allowed by 4.5/2: test case trailing-space
  * Make CNAME loop result in unknown host: test case ptr-cname-loop
  * Test case and fix for mixed case CNAME loop, test case ptr-cname-loop

Version 2.0.11 - December 5, 2014
  * Fix another bug in SPF record parsing that caused records with terms
    separated by multple spaces as invalid, but they are fine per the ABNF
  * Downcase names in additional answers returned by DNS before adding
    to cache, since case inconsistency can cause PTR match failures (initial
    patch thanks to Joni Fieggen) and other problems.

Version 2.0.10 - September 2, 2014
  * Fix bug in SPF record parsing that caused all 'whitespace' characters to
    be considered valid term separators and not just spaces
  * Fixed multiple bugs in temperror processing that would lead to tracebacks
    instead of correct error processing
  * Fix AAAA not flagged as bytes when strict=2
  * Include '~' as safe char in url quoted macro expansion

Version 2.0.9 - April 29, 2014
  * Update for new SPF standards track RFC 7208
    - Add processing for new void lookups processing limit
    - Default SPF process timeout limit to 20 seconds per RFC 7208 4.6.4
    - Change default DNS timeout to 20 seconds in DNSLookup to better match
      RFC 7208 4.6.4
    - Make mx lookups > 10 a permerror per RFC 7208 and mx-limit test
    - Add RFC 7208 specific test suite and make allowance for RFC 7208 changes
      in RFC 4408 test suite
    - Convert YAML tests to TestCases, and have testspf.py return success/fail.