Samples randomly use JettyServer or TomcatServer

Samples (for example feed-aggregator) randomly run with the embedded JettyServer or the TomcatServer.

To reproduce the issue, do ant run in feed-aggregator several times, some executions will use Jetty, others will use Tomcat.

This is probably an issue with how the release distro is built, incorrectly placing both tuscany-host-tomcat and tuscany-host-jetty on the classpath of sca-manifest.jar and/or sca-tuscany-all.jar.