Convert port-allocator-plugin from svn to git.
Also update parent pom to 1.392 as per
http://meetings.jenkins-ci.org/jenkins/2011/jenkins.2011-10-26-18.04.html
updated maven pom to use repo.jenkins-ci.org repository
* Add IntelliJ files to .gitignore
* Fix typo in help file.
JENKINS-11255 Pooled port allocation support (+ implement ResourceActivity to queue builds instead of blocking after start).