Turn more configuration files in samples

Similar to other configuration files, this commit
renames event-viewer.yaml and hornetq-configuration.xml
into .sample files; the advantage being that this
makes a bit easier to install deployment-specific
RPMs, without needing to --replacefiles anything.
Make menu shortcuts more mac-friendly

Behaviour on linux/windows remains unchanged.

Conflicts:
	yamcs-core/src/main/java/org/yamcs/ui/eventviewer/EventViewer.java