Re-organized SDG dependency version properties in gradle.properties.
Additional changes to the CacheClusterConfigurationIntegrationTest to ascertain the test case (testClusterConfiguration) failure in the Bamboo CI environment.  Modified ProcessExecutor to add to the Java launcher command-line of the forked Java process any System Properties that start with 'spring.gemfire.'  Added a write(:File, contents:String) method to the FileUtils utility class.