Add -cp to option help for compiler commands

Fixes gh-178

spring-boot-cli/src/main/java/org/springframework/boot/cli/command/OptionHandler.java

@@ -168,6 +168,9 @@ public class OptionHandler {
 			for (String option : descriptor.options()) {
 				this.options.add((option.length() == 1 ? "-" : "--") + option);
 			}
+			if (this.options.contains("--cp")) {
+				this.options.add("-cp");
+			}
 			this.description = descriptor.description();
 		}
 

spring-boot-cli/src/test/java/org/springframework/boot/cli/CliTester.java

@@ -98,7 +98,7 @@ public class CliTester implements TestRule {
 		final String[] sources = new String[args.length];
 		for (int i = 0; i < args.length; i++) {
 			String arg = args[i];
-			if (arg.startsWith("--")) {
+			if (arg.startsWith("-")) {
 				sources[i] = arg;
 			}
 			else {