ETCH-290 Removed Static mutex inside of EtchConnection

EtchConnections suffer to a Deadlock with multiple EtchSessions /
Connections. Removing the static mutex solves this issue.

Change-Id: If9c5ed101a247a33245a750467e64b1b37dda410

git-svn-id: https://svn.apache.org/repos/asf/etch/trunk@1579566 13f79535-47bb-0310-9956-ffa450edef68