[maven-release-plugin] prepare release xmlschema-2.1.0

git-svn-id: https://svn.apache.org/repos/asf/webservices/xmlschema/trunk@1560139 13f79535-47bb-0310-9956-ffa450edef68
[maven-release-plugin] prepare for next development iteration

git-svn-id: https://svn.apache.org/repos/asf/webservices/xmlschema/trunk@1560141 13f79535-47bb-0310-9956-ffa450edef68