Update configuration of Spring IO plugin

This PR updates the configuration of the IO plugin to use an external property, platformVersion, and to only apply the plugin when this property is set. This removes the declaration of a snapshot dependency from the normal build configuration and also breaks a circular dependency between the projects that are in the Platform and the Platform itself.

The commit also applies the configuration that was applied to the standard test task, other than code coverage, to the new test tasks that are created by the Spring IO plugin.

Two redundant Hibernate mapping files have been deleted. With more recent versions of Hibernate the presence of these files was causing test failures due to duplicate mappings. The normal tests continue to pass without the two mapping files.