A place to store all core extensions.
As stated in diego.init.Module, while functionalities such as sending mail and using JDBC to interact with a database are useful, they are not exactly core to the functioning of the web framework.
Most other features - Authorization providers, template engines, http configuration - have sensible defaults that
can be placed in reference.conf and are therefore considered "core" features. The functionalities
implemented here will be considered core extensions since they are implementations of functionalities that are
common in the development of web applications, but not core to the framework. These extensions may even be
refactored into their own discrete packages in future versions as we seek to minimize the framework's size.