Update Tomcat multi connectors sample to configure HTTPS declaratively

[wilkinsona]

From @arosini on Gitter:

Well the documentation for multiple connectors (http://docs.spring.io/spring-boot/docs/current/reference/html/howto-embedded-servlet-containers.html#howto-configure-ssl) says "It’s recommended to use application.properties to configure HTTPS as the HTTP connector is the easier of the two to configure programmatically". Then the project it links to as an example (https://github.com/spring-projects/spring-boot/tree/v1.2.7.RELEASE/spring-boot-samples/spring-boot-sample-tomcat-multi-connectors) configures the HTTPS connector via Java configuration. It was a bit confusing to me, and I thought it might save somebody that confusion in the future.