Remove old SDG test framework classes.

Refactor and cleanup test classes in the SDG test suite using the old SDG test framework to now use STDG.

Resolves gh-296.

src/main/asciidoc/reference/gemfire-bootstrap.adoc

@@ -160,7 +160,7 @@ the following (which comes from {sdg-acronym}'s test suite):
       <value-constraint>org.springframework.data.gemfire.repository.sample.User</value-constraint>
       <cache-loader>
         <class-name>
-          org.springframework.data.gemfire.support.SpringContextBootstrappingInitializerIntegrationTest$UserDataStoreCacheLoader
+          org.springframework.data.gemfire.support.SpringContextBootstrappingInitializerIntegrationTests$UserDataStoreCacheLoader
         </class-name>
       </cache-loader>
     </region-attributes>