Download xapi-core-util JAR file with all dependencies

This module contains static services and default implementations for other core services. In order to keep core dependencies as clean as possible, we avoid accessing helpers like X_Inject or X_Reflect unless they are needed to perform a task. For example, ReflectionService and it's default implementation don't have to know about X_Inject, but it's public service X_Reflect does. So, the implementation goes in xapi-core-reflect, and the static accessor goes in xapi-core-util.