Medium: Run as root instead of RUNASIS mode when tomcat_user is not set.

It is more consistent behavior with jboss RA, and also eliminates a bug
when catalina_rotate_log=YES in RUNASIS mode.

This change should not affect to any cluster configurations because
Pacemaker/lrmd always invoke a RA as root.
It only affects when you run the RA as a regular user outside of the cluster
but it is not very common usage.