Add ExitStatus to Command.run()

The main difference for now is the removal of the --nohup
(slightly hacky) option in TestCommand. Now a TestCommand
can signal to its caller that it wants to be hung up.

Fixes gh-975

spring-boot-tools/spring-boot-loader-tools/src/main/java/org/springframework/boot/loader/tools/RunProcess.java

@@ -48,11 +48,11 @@ public class RunProcess {
 		this.command = command;
 	}
 
-	public void run(String... args) throws IOException {
-		run(Arrays.asList(args));
+	public int run(String... args) throws IOException {
+		return run(Arrays.asList(args));
 	}
 
-	protected void run(Collection<String> args) throws IOException {
+	protected int run(Collection<String> args) throws IOException {
 		ProcessBuilder builder = new ProcessBuilder(this.command);
 		builder.command().addAll(args);
 		builder.redirectErrorStream(true);
@@ -74,6 +74,12 @@ public class RunProcess {
 			catch (InterruptedException ex) {
 				Thread.currentThread().interrupt();
 			}
+			try {
+				return this.process.exitValue();
+			}
+			catch (IllegalThreadStateException e) {
+				return 1;
+			}
 		}
 		finally {
 			this.endTime = System.currentTimeMillis();