TomcatEmbeddedServletContainer should fails fast

Hi,

when Spring Boot application uses Tomcat embedded servlet container and started twice,
there will be a BindException (adress already in use), which is obviously correct.
But, the application starts and only the exception is logged.

I would expect, that the application will automatically shut down, when there are exceptions during startup phase.
Because, this is the behavior like using Jetty embedded container.

This patch simple re-throws the Excpetion, so that the application will do System.exit() and shuts down.

Regards
Martin