Add ComponentScan aliases on SpringBootApplication

Add aliases for `@ComponentScan`attributes on `@SpringBootApplication`
so that it is possible to customize how the component scan should be
applied on the project.

Previously, one would have to revert to `@EnableAutoConfiguration` to
achieve the same result.

Closes gh-3368

spring-boot-docs/src/main/asciidoc/using-spring-boot.adoc

@@ -696,6 +696,9 @@ The `@SpringBootApplication` annotation is equivalent to using `@Configuration`,
 	}
 ----
 
+NOTE: `@SpringBootApplication` also provides aliases to customize the attributes of
+`@EnableAutoConfiguration` and `@ComponentScan`.
+
 
 
 [[using-boot-running-your-application]]