Opinionated defaults for WebSockets:
* If spring-websocket is on the classpath and so is
the Tomcat WSci initializer then it is added to the context
* A DefaultSockJsService is added if none is present
* User has only to define @Beans of type WebSocketHandler with
name starting "/"
* Each one is converted to a SockJsHttpRequestHandler and
mapped to "/<beanName>/**"
This reverts commit e99d2199d8b613f6099eb3fd577b9700b4050b8f.
The main spring-boot project should not have compile scope dependencies
to any org.slf4j artifacts.
Rework main build POM to be an aggregator pom that does not inherit
from any parent. Introduce new spring-boot-dependencies module to
act as a parent for both spring-boot-starter-parent and
spring-boot-parent.