Simplified handling of temporary files in test class.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/configuration/trunk@1482081 13f79535-47bb-0310-9956-ffa450edef68
Added ReadWriteSynchronizer class.

This is an implementation of the Synchronizer interfaced based on the
java.util.concurrent.locks.ReentrantReadWriteLock. It can be used to make
configurations thread-safe if they are accessed concurrently.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/configuration/trunk@1482082 13f79535-47bb-0310-9956-ffa450edef68