streamsx.sttgateway toolkit v2.2.8

This release has changes for catching the exception thrown when a VGW connection handle can't be found in the connection map of the IBMVoiceGatewaySource operator. It also has another change to wait for the Boost ASIO service thread's run loop to exit before shutting down that operator in order to avoid the "Port in use. Underlying Transport Error" problem when that operator is started immediately after a shutdown. Please always use the tar.gz file that has version number, date, time, MD5 and sha1.

What's new: CHANGELOG.md