#1 - Initial commit.

Extracted sample application from SalesPoint repository. Moved to Spring Data JPA for persistence. Moved static resources (tempaltes, JavaScript and CSS) into default location to avoid the need for configuration.

Changed Guestbook to become a Spring Data repository and moved initializing code into the main Application class. Polished controller implementations to make use of correct HTTP verbs, Java 8's Optional etc.

TODO: JavaScript of the AJAX implementation doesn't seem to work correctly /o\.