Add spring war command

Add a `war` command to the CLI to generate WAR archives.

Fixes gh-925
Closes gh-4168

spring-boot-cli/src/it/resources/war-command/war.groovy

@@ -0,0 +1,16 @@
+package org.test
+
+@RestController
+class WarExample implements CommandLineRunner {
+
+	@RequestMapping("/")
+	public String hello() {
+		return "Hello"
+	}
+
+	void run(String... args) {
+		println getClass().getResource('/org/apache/tomcat/InstanceManager.class')
+		throw new RuntimeException("onStart error")
+	}
+
+}