Correct message that is logged when load-on-startup servlet fails to load.
It was logging context name instead of servlet name.
Also correct message key. The message belongs to StandardContext. It is not used anywhere else. It is not used by StandardWrapper.

To test: uncomment CGIServlet and its mapping in conf/web.xml and look for messages in localhost.$DATE.log file.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1640652 13f79535-47bb-0310-9956-ffa450edef68