Upgrade Tomcat to the latest 8.0.x release

Summary

We are currently on 8.0.17 and have already been bitten by a bug in it:

https://bz.apache.org/bugzilla/show_bug.cgi?id=57476

We should upgrade to the latest to get the latest bugfixes.

Also, there have been a number of recent CVEs involving Tomcat, most of which involve SecurityManager, which I believe we do not currently use.

http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-5174
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-0706
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-0714
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-0763

However, these are related to other aspects of Tomcat:

http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-5345
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-5346
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-5351 (probably doesn't affect us)

Updating Tomcat to one of these versions would appear to patch all of the above CVEs:

• Apache Tomcat 9.0.0.M3
• Apache Tomcat 8.0.32
• Apache Tomcat 7.0.68
• Apache Tomcat 6.0.45