Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=51526
o.a.catalina.startup.Tomcat.addWebapp(...) will process web application's context.xml when it is presented in the provided baseDir.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1517941 13f79535-47bb-0310-9956-ffa450edef68