better hot-reload control in tomcat container

Hot-reloading is done automatically by checking dev bundles every 2 seconds. This does not permit the IDE to control at which time the bundles at which the bundles are taken in account. We're going to expose in JMX a bean for controlling the reset instead.

By default, the timer will be disabled. To re-activate, just edit the launcher.properties template file and set the timer property org.nuxeo.app.installReloadTimer to true.