Correct the return value for StandardContext.getResourceOnlyServlets()
so that multiple names are separated by commas. Identified by Coverity
Scan and fixed based on a patch by Felix Schumacher.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1621731 13f79535-47bb-0310-9956-ffa450edef68