TomcatDeployer should look for context.xml in META-INF as well as WEB-INF

Tomcat documentation (http://jakarta.apache.org/tomcat/tomcat-5.5-doc/config/context.html) tells users to place a context.xml in the webapp's META-INF dir. We look for it in WEB-INF, since WEB-INF is a required dir and META-INF isn't.

If context.xml isn't found in WEB-INF, we should look in META-INF as well. Keep WEB-INF as the first place to look so as not to break any existing apps that have a left-over file in META-INF.