[maven-release-plugin] prepare release 3.8.0

git-svn-id: https://svn.apache.org/repos/asf/activemq/activemq-cpp/trunk@1515429 13f79535-47bb-0310-9956-ffa450edef68
[maven-release-plugin] prepare for next development iteration

git-svn-id: https://svn.apache.org/repos/asf/activemq/activemq-cpp/trunk@1515431 13f79535-47bb-0310-9956-ffa450edef68