LiveReload is currently not installed by default as part of JBoss Tools 4.6 or Devstudio 12, as it was deprecated in 4.5.3 / 11.3.
But it's still available in the update site, and on Red Hat Central. Just find the connector / feature, and install it. Here's a walkthrough for installing it from Central:
If it doesn't work after that, please see [JBIDE-25990] FrameworkEvent ERROR - JBoss Issue Tracker and feel free to comment on that issue that you're having the same (or similar) problems. It would be helpful to include your version of Eclipse, devstudio, jbosstools, your operating system and version, and your JDK vendor & version.