Added backward compatible data loader and a corresponding test case.

There are several incompatibilities in XStream 1.4 that resulted in our
changing the core, but according to the text search on all the public
plugins, none of these changes affect the 600+ plugins we have today.

However, it is still possible that there are some parts of XStream 1.3
that plugins depend on but the core doesn't depend on --- we won't be
able to tell those problems at this point.

Not sure what has happened --- perhaps some of the markers were off and
that confused the update script?

Will need to watch out for the next RC run.

Add/update Chinese (traditional) translation.

Fixed French Translation

Fixes: Maven2 builds with non-standard test mojos failed.

Added the -noCertificateCheck option (the option name is consistent with
the slave.jar) that lets users bypass the HTTPS certificate check.

This allows trivial man-in-the-middle attack, so HTTPS will no longer be
HTTPS.

[FIXED JENKINS-16844] MenuItem.post allows context menu items like Build Now to send a POST request.
Currently just shows a hover notification; TBD if there are use cases for displaying the response.

Not observed in actual usage, but reproducible (for me at least, though apparently not ci.jenkins-ci.org) in a test:
java.lang.AssertionError: null
    at jenkins.model.lazy.AbstractLazyLoadRunMap.load(AbstractLazyLoadRunMap.java:628)
    at jenkins.model.lazy.AbstractLazyLoadRunMap.all(AbstractLazyLoadRunMap.java:581)
    at jenkins.model.lazy.AbstractLazyLoadRunMap.entrySet(AbstractLazyLoadRunMap.java:243)
    at java.util.AbstractMap$2$1.<init>(AbstractMap.java:378)
    at java.util.AbstractMap$2.iterator(AbstractMap.java:377)
    at hudson.util.RunList.iterator(RunList.java:103)
    at hudson.util.RunList.size(RunList.java:114)
    at hudson.maven.MavenProjectTest.testDeleteSetBuildDeletesModuleBuilds(MavenProjectTest.java:159)

[JENKINS-16917] hudson.plugins.downstream_ext.DownstreamTrigger.DescriptorImpl should not be extending BuildTrigger.DescriptorImpl since it does not produce a BuildTrigger from newInstance.
(Generally there is no reason to subclass a Descriptor type which is already an @Extension rather than an explicit abstract supertype, but this is a bit more conservative change than just making it final.)

translation cleanup

purged some dislocated messages that survived my former cleanups

removed translations from GlobalSecurityConfiguration and jenkins/model/Jenkins
that should only exist in GlobalCloudConfiguration

removed translations from GlobalSecurityConfiguration and jenkins/model/Jenkins
that should only exist in GlobalQuietPeriodConfiguration and config-quietPeriod
added translations based on messages from corresponding locations

removed translations from GlobalSecurityConfiguration and jenkins/model/Jenkins
that should only exist in GlobalSCMRetryCountConfiguration and config-retryCount
added translation based on messages from corresponding locations
corrected wrong property names

Conflicts:
	core/src/main/resources/jenkins/model/Jenkins/help-rawBuildsDir.html
	core/src/main/resources/jenkins/model/Jenkins/help-rawWorkspaceDir.html

[FIXED JENKINS-16630] Human readable file size method returns ",00" for files with byte length 0