Begin the deprecation of auto-idna for x509.DNSName (#3830)

* Begin the deprecation of auto-idna for x509.DNSName

Refs #3357

* fix warning

* py3k fixes

* fix docs

* sigh

* flake8

* these are words

* words

* tests for coverage

* another test

* do idna things

* more idna things
diff --git a/tests/test_x509_revokedcertbuilder.py b/tests/test_x509_revokedcertbuilder.py
index e3a0650..9fc5eaa 100644
--- a/tests/test_x509_revokedcertbuilder.py
+++ b/tests/test_x509_revokedcertbuilder.py
@@ -146,7 +146,7 @@
             x509.InvalidityDate(datetime.datetime(2015, 1, 1, 0, 0)),
             x509.CRLReason(x509.ReasonFlags.ca_compromise),
             x509.CertificateIssuer([
-                x509.DNSName(u"cryptography.io"),
+                x509.DNSName(b"cryptography.io"),
             ])
         ]
     )
@@ -180,7 +180,7 @@
             datetime.datetime(2015, 1, 1, 0, 0)
         )
         certificate_issuer = x509.CertificateIssuer([
-            x509.DNSName(u"cryptography.io"),
+            x509.DNSName(b"cryptography.io"),
         ])
         crl_reason = x509.CRLReason(x509.ReasonFlags.aa_compromise)
         builder = x509.RevokedCertificateBuilder().serial_number(