Application engine

• Adding a workspace configuration class, matching a JSON file
  
  The workspace configuration contains a property 'applications', an array of ApplicationConfiguration object.
  
  An application configuration is a specific URL binding, and navigation information (localized message and icon).

• Adding a Message class to store a localizable message.

• Adding an hello world application to demonstrate how an user can write a new application.

• Navigation shows these customs applications.

• Entry point calls relevant application controller.