[FIXED JENKINS-38721, JENKINS-37282] - NPE in "CauseOfInterruption.UserInterruption" when user is missing (#2630)

* [FIXED JENKINS-38721] - Prevent NPE during rendering of "CauseOfInterruption.UserInterruption" when user is missing

It is a regression introduced in JENKINS-36594

* [JENKINS-38721] - Fix typo

[SECURITY-360] 2016/11/16 security fix for 1.625

Merge branch 'SECURITY-360-test' into security-stable-1.625

Extend ysoserial coverage for latest cases [SECURITY-317]

Make sure LDAPAttribute gets rejected.

[SECURITY-360] system property to disable CLI

Polish translations

This basically is a convenient version of
https://github.com/jenkinsci-cert/SECURITY-218.

During the course of discussing how to fix SECURITY-360, it was agreed
by the CERT team that we provide this switch.