[bs-19] Add samples and CLI support for Spring Integration

$ cd spring-bootstrap-cli
    $ export SPRING_HOME=target
    $ src/main/scripts/spring run samples/integration.groovy

The big disadvantage at the moment is that there is no goo way to
detect Spring Integration in the AST (at least not as good as @Enable*).
So for now we are looking for @MessageEndpoint or a class name with
SpringIntegration in it.

[#48151147]

spring-bootstrap-cli/samples/service.groovy

@@ -1,6 +1,5 @@
 package org.test
 
-@GrabResolver(name='spring-snapshot', root='http://repo.springframework.org/snapshot')
 @Grab("org.springframework.bootstrap:spring-bootstrap-service:0.0.1-SNAPSHOT")
 
 @Controller