https://issues.apache.org/bugzilla/show_bug.cgi?id=44312
Log an error if there is a conflict between Host and Alias names.
Improve addHost, addHostAlias, removeHost, removeHostAlias methods in Mapper to avoid occasionally removing a wrong host. (Add a check of whether the expected object was found, and whether it is the primary Host or an Alias).

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1604895 13f79535-47bb-0310-9956-ffa450edef68