[maven-release-plugin] prepare for next development iteration
Fixed maven-gpg version

Change-Id: Iac1f72394320d9f611c9718eebf4122fab4c579d
Fixed maven-gpg version

Change-Id: I4cf89719e1c1a82c91bb7a2c34877d1fbe099fa0
Package version updated to release version
[maven-release-plugin] prepare release kws-content-api-4.3.15