MGASA-2018-0066 Updated python-mistune packages fix security vulnerabilities

mistune.py in Mistune 0.7.4 allows XSS via an unexpected newline such as in java\nscript: or a crafted email address, related to the escape and autolink functions CVE-2017-15612. A cross-site-scripting vulnerability was found in python-mistune CVE-2017-16876...