[JENKINS-22639] Don't record changes to AbstractCloudSlaves or EphemeralNodes

This can result in high load when there are nodes coming online and offline quickly.
Merge pull request #27 from jenkinsci/ephemeral

[JENKINS-22639] Don't record changes to AbstractCloudSlaves or Ephemeral Nodes
Fix proposal for NPE in ComputerHistoryListener.onConfigurationChange
method. Our jenkins faced some restart issue with the following
stacktrace. So better to ensure the nodes list is defined on the first
run.

hudson.util.HudsonFailedToLoad: java.lang.NullPointerException
  at hudson.WebAppMain$3.run(WebAppMain.java:234)
Caused by: java.lang.NullPointerException
  at
hudson.plugins.jobConfigHistory.ComputerHistoryListener.onConfigurationChange(ComputerHistoryListener.java:29)
  at
hudson.model.AbstractCIBase.updateComputerList(AbstractCIBase.java:195)
  at jenkins.model.Jenkins.updateComputerList(Jenkins.java:1220)
  at jenkins.model.Jenkins.<init>(Jenkins.java:852)
  at hudson.model.Hudson.<init>(Hudson.java:82)
  at hudson.model.Hudson.<init>(Hudson.java:78)
  at hudson.WebAppMain$3.run(WebAppMain.java:222)
Merge pull request #39 from williambernardet/master

NPE on ComputerHistoryListener.onConfigurationChange
[maven-release-plugin] prepare release jobConfigHistory-2.10
[maven-release-plugin] prepare for next development iteration
Avoid tracking changes for cloud slave as well
Merge pull request #40 from recampbell/cloud-onchange

Avoid tracking changes for cloud slave as well
Do not use the Callable from remoting frivolously; the signature changed in the SECURITY-144 fix.
Merge pull request #41 from jglick/test-against-new-baseline

Allow plugin to compile against newer baselines
Start to experiment with GitHistoryDao