Username/password encoding in HTTP basic auth is currently broken for non-ASCII password.

Example with user user and password unusual-char-é. With curl it works as expected:

curl -v 'http://user:unusual-char-%C3%A9@localhost:5984/'

> GET / HTTP/1.1
> Authorization: Basic YWxpY2U6YWRyaWVuPTohw6k=
> 
< HTTP/1.1 200 OK

But with couchdb-python the string is decoded from utf-8 then re-encoded into latin1, causing an incorrect Authorization header:

url = 'http://user:unusual-char-%C3%A9@localhost:5984/'
couchdb.Server(url).version()

> GET / HTTP/1.1
> Authorization: Basic dXNlcjp1bnVzdWFsLWNoYXIt6Q==
> 
< HTTP/1.1 401 Unauthorized