WebSphere WAR Deployment Timeout Exception

If you ever get an exception deploying a large WAR file on WebSphere here's the error, and how to fix it.

EJPPH0036I: Timeout reached after 300 seconds.
Explanation: A timeout was received prior to the expected notification event.
User Response: Increase the value of the property was.notification.timeout in DeploymentService.properies.

The stack trace may contain the exception com.ibm.wps.pe.mgr.exceptions.AppServerWarInstallException:

The DeploymentService.properties is located in shared/app/config/services under your websphere install root.