Relocating the PomDevelopersPlugin from the gradle-contacts-plugin

Moved the PomDevelopersPlugin from the gradle-contacts-plugin.  Also added a dependency on the gradle-info-plugin and the gradle-contacts-plugin.

Related to:
https://github.com/nebula-plugins/gradle-info-plugin/pull/4
https://github.com/nebula-plugins/gradle-contacts-plugin/pull/2