Add method to shutdown all connections

All connections are closed and the method waits until the connection
threads are terminated.

Change-Id: I079d216bd7a101514fbe10b1f1542e7033f8ea6e

git-svn-id: https://svn.apache.org/repos/asf/etch/trunk@1679594 13f79535-47bb-0310-9956-ffa450edef68
3 files changed