First proper draft of DSL for Groovy Commands

Users can declare or Command, OptionHandler classes in an init script
or they can use a DSL, e.g.

command("foo") { args -> println "Do stuff with ${args} array" }

or

command("foo") {
  options { option "bar", "Help text for bar option" ithOptionArg() ofType Integer }
  run { options -> println "Do stuff with ${options.valueOf('bar')}" }
}

spring-boot-cli/src/test/resources/commands/handler.groovy

@@ -31,7 +31,6 @@ class TestCommand extends OptionHandler {
 	void run(OptionSet options) {
 		// Demonstrate use of Grape.grab to load dependencies before running
 		println "Clean: " + Git.open(".." as File).status().call().isClean()
-		org.springframework.boot.cli.command.ScriptCommandTests.executed = true
 		println "Hello ${options.nonOptionArguments()}: ${options.has('foo')}"
 	}