Use no-fork variants / pluginManagement only for plugins

[khmarbaise]

Many of the plugins like javadoc, jdepend, jxr have a goal -no-fork that saves time and is usually the best way to call plugins.
You can also use properties instead of configuring the whole plugin.
So you can separate definition of the plugins via pluginManagement makes it easier for later refactoring into a general parent.