[FIXED SECURITY-134] Restrict access to admin monitor info page

This could contain sensitive information in the list of solutions
provided. It also shows the path to JENKINS_HOME, exposing OS and
configuration information.
[FIXED JENKINS-23526] Tolerate 'null' result when used creatively
Merge pull request #1296 from daniel-beck/JENKINS-23526

[FIXED JENKINS-23526] Tolerate 'null' result when used creatively
[maven-release-plugin] prepare release jenkins-1.569
[maven-release-plugin] prepare for next development iteration
updated changelog for release
updated changelog as a part of the release
merged back the RC branch
creating an RC branch
the trunk is toward 1.571-SNAPSHOT
Merge pull request #1283 from daniel-beck/SECURITY-134

[FIXED SECURITY-134] Restrict access to admin monitor info page
Noting #1283