add support for ipv6

Author: jdkandersson

juju/client/connection.py

@@ -694,7 +694,9 @@ def https_connection(self):
 
         """
         endpoint = self.endpoint
-        host, remainder = endpoint.split(':', 1)
+        # Support IPv6 by right splitting on : and removing [] around IP address for host
+        host, remainder = endpoint.rsplit(':', 1)
+        host = host.strip("[]")
         port = remainder
         if '/' in remainder:
             port, _ = remainder.split('/', 1)