Defaults values for @SpringConfiguration and @SpringAnnotationConfiguration

The idea is similar to the 'convention over configuration' approach from Spring Test.

When configuring test with @SpringConfiguration when no XML configuration will specified the extension by default should try to load file with exact same name as the test class and additional '-context.xml' suffix e.g.

For class org.sample.Test the default resource location should be org/sample/Test-context.xml.

In case of @SpringAnnotationConfiguration when no class or package has been specified the extension by default should scan for static (non final) class annoated with @Configuration and use it when instantiating the AnnotationApplicationContext.