FIX SCRAM-SHA-1-PLUS

The mechanism name was being correctly de-plussed, but then we used the
original, -PLUS, name to extract the hash, finding SHA-1-PLUS and therefore
finding no match.

Test-Information:

Tested with Sleek against an Isode M-Link with SCRAM-SHA-1-PLUS available.

Author: dwd

sleekxmpp/thirdparty/suelta/mechanisms/scram_hmac.py

@@ -32,7 +32,7 @@ class SCRAM_HMAC(Mechanism):
             name = name[:-5]
             self._cb = True
 
-        self.hash = hash(self.name[6:])
+        self.hash = hash(name[6:])
         if self.hash is None:
             raise SASLCancelled(self.sasl, self)
         if not self.sasl.tls_active():