Started with a fork of the HipChat plugin:

https://github.com/jlewallen/jenkins-hipchat-plugin

Which was, in turn, a fork of the Campfire plugin.

1. Get a Slack account: https://slack.com/
2. Configure the Jenkins integration: https://my.slack.com/services/new/jenkins-ci
3. Install this plugin on your Jenkins server
4. Configure it in your Jenkins job and add it as a Post-build action.

Install Maven and JDK. This was last build with Maven 3.2.5 and OpenJDK 1.7.0_75 on KUbuntu 14.04.

Run unit tests

mvn test

Create an HPI file to install in Jenkins (HPI file will be in target/slack.hpi).

mvn package