Regression related to HUDSON-2988 (special display of suites).

* commit '9a45f788':
  HUDSON-8252 FIXED update changelog.html appropriately
  HUDSON-8252 FIXED offline slaves wasting space in status list

There is a lot of wasted space on the Build Executor Status when
slave nodes are offline. The space can be reclaimed by simply
not displaying offline executors for offline slaves.

This is actually what I was expecting, as evident in the javadoc of XmlFile.unmarshal()

Add enforcer version to the pom so we don't try and get 1.1-SNAPSHOT (as we want reproduceable builds!)

Conflicts:
	core/src/main/java/hudson/tasks/MailSender.java

by willemv: Fixed boundary check error, and made variable names clearer.

Conflicts:
	.gitignore

Correct (incorrect) comment in CronTabTest

java.net migration means these services are no longer available. We can recreate them from Maven repository

importing plugin POM from rev.37164. Since this file is controlled by the core release process, better to put it here

[FIXED HUDSON-7937] Restarting Hudson via debian init script didn't wait for the process to really terminate.