Update changelog.txt for 1.0.0 release

git-svn-id: https://svn.apache.org/repos/asf/felix/trunk@1484851 13f79535-47bb-0310-9956-ffa450edef68
[maven-release-plugin] prepare release org.apache.felix.inventory-1.0.0

git-svn-id: https://svn.apache.org/repos/asf/felix/trunk@1484855 13f79535-47bb-0310-9956-ffa450edef68
[maven-release-plugin] prepare for next development iteration

git-svn-id: https://svn.apache.org/repos/asf/felix/trunk@1484857 13f79535-47bb-0310-9956-ffa450edef68