Smack should be able to handle "single equals sign" SASL responses

Fixed with 2b83decc89a1311404722bfb53c4596cb9a7fd58, which unfortunately mentions the wrong issue key ( instead of -732).

reminds of SMACK-324. The "single equals sign" requirement of RFC 6120 strikes again. Note that was a false positive: The behavior of sending a single equals sign is standards conform. That's why the behavior was re-established in recent Smack versions.