logging improvements

[lukn]

passing a logger reveals many errors, but the result is only of limited value:

e.g.
dkimpy : ERROR b'include:spf.slynet.ch'
error is caused by bogus txt record:
selector._domainkey.example.com. 14400 IN TXT "include:spf.slynet.ch"
a little extra message pointing this out would be appreciated.

dkimpy : ERROR bad version
error is cause by malformed txt record:
selector._domainkey.example.com. 14400 IN TXT "v=k=rsa;t=s;p=MIGf..."

dkimpy : ERROR b'"k=rsa'
error is cause by malformed txt record:
selector._domainkey.example.com. 14400 IN TXT "\"k=rsa; p=MIGf..."

dkimpy : ERROR b'DKIM1'
dkimpy : ERROR b''
(sorry, no identifiable examples for these...)

Additionally, in python3 dns error messages want to be converted to unicode string first (using decode()) (I'm using dnspython as dns query backend).

[Scott Kitterman (kitterman)]

Do you have examples for these? It looks easy enough to fix, but it'd be much easier to verify they are fixed if you would provide the script you're using to test these.