Initial fork of certbot-dns-servfail; talks to the yeil dns-server RPC

DNS-01 authenticator that walks up the labels of the validation name,
calls findzone on the dns-server RPC to locate the registered parent
zone, then addrecord/deleterecord around the TXT challenge.

Auth is HTTP Basic with the shared rpc key (matches the protocol the
yeil DNS web app uses in dns/src/lib/rpc.ts).

setup.py

@@ -0,0 +1,20 @@
+from setuptools import setup, find_packages
+
+setup(
+    name="certbot-dns-yeil",
+    version="1.0.0",
+    description="yeil DNS Authenticator plugin for Certbot",
+    url="https://git.eskimo.dev/Yeil/certbot-dns-yeil",
+    author="yeil",
+    license="MIT",
+    packages=find_packages(),
+    install_requires=[
+        "certbot>=1.1.0",
+        "zope.interface",
+    ],
+    entry_points={
+        "certbot.plugins": [
+            "dns-yeil = certbot_dns_yeil.dns_yeil:Authenticator",
+        ],
+    },
+)