Use current versions for parent and plugins.

* oss-parent: 7 -> 9
* maven-gpg-plugin: 1.4 -> 1.5
* nexus-staging-maven-plugin: 1.4.7 -> 1.6.2
Change inceptin year from 2013 to 2014.

Time goes by.
Use autoReleaseAfterClose for Nexus.

Avoid the manual step.