[JENKINS-26677] Avoid using ServletException from SlaveComputer since it can break calls to SlaveComputer.getChannelToMaster. (#3778)

java.lang.NoClassDefFoundError: javax/servlet/ServletException
	at hudson.util.ProcessTree.get(ProcessTree.java:399)

Bump ATH version to one that support Selenium 3

* [CORE-626] remove ZeroClipboard and replace with pure js replacement

* remove css rule used for testing

* Poke the build

Miscellaneous minor fixes

Update triggerRemotely documentation

[JENKINS-55197] Correction of the InstallUncaught exception

Fixing tests which attempted to restart the Surefire booter JVM

Upgrade to 3.28 version of Remoting.

Amends code added in https://github.com/jenkinsci/jenkins/pull/2082.
java.lang.RuntimeException: Unexpected issues encountered during cleanUp: offset 0, count -1, length 5
	at jenkins.model.Jenkins.cleanUp(Jenkins.java:3319)
	at org.jvnet.hudson.test.JenkinsRule.after(JenkinsRule.java:495)
	at org.jvnet.hudson.test.JenkinsRule$1.evaluate(JenkinsRule.java:565)
	at org.junit.internal.runners.statements.FailOnTimeout$CallableStatement.call(FailOnTimeout.java:298)
	at org.junit.internal.runners.statements.FailOnTimeout$CallableStatement.call(FailOnTimeout.java:292)
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
	at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: java.lang.StringIndexOutOfBoundsException: offset 0, count -1, length 5
	at java.base/java.lang.String.checkBoundsOffCount(String.java:3304)
	at java.base/java.lang.String.<init>(String.java:465)
	at hudson.TcpSlaveAgentListener$PingAgentProtocol.connect(TcpSlaveAgentListener.java:416)
	at hudson.TcpSlaveAgentListener.shutdown(TcpSlaveAgentListener.java:196)
	at jenkins.model.Jenkins._cleanUpShutdownTcpSlaveAgent(Jenkins.java:3548)
	at jenkins.model.Jenkins.cleanUp(Jenkins.java:3294)
	... 6 more

Suppressing a flaky test

https://ci.jenkins.io/job/Core/job/jenkins/job/master/1179/execution/node/38/log/?consoleFull
[WARNING] Corrupted stdin stream in forked JVM 2. See the dump file /home/jenkins/workspace/Core_jenkins_master-CZB5BLBJFXZE2BKR63DSXQKXRZJAOWBX73QP55GU5KMX7AHAF6CQ/test/target/surefire-reports/2018-12-12T10-57-04_077-jvmRun2.dumpstream

https://ci.jenkins.io//job/Core/job/jenkins/job/master/1179//testReport/junit/hudson.model/QueueTest/Windows_jdk8___Windows_Publishing___testBlockBuildWhenUpstreamBuildingLock/

Remove duplicate @Ignore failing the compilation

[JENKINS-54325] Add support for multiple footers in SimplePageDecorator

Co-Authored-By: Ndaniel-beck <daniel-beck@users.noreply.github.com>

Suppressing some tests which fail in CI

Fixed in https://github.com/jenkinsci/jenkins/pull/3795

Improve test assertion

[JENKINS-55081] SEC-904 related test failing on java 11

* [JENKINS-52869] Show error messages on user creation

* Restore support for general signup error