Remove support for InitCommand outside REPL

In this commit we retain "init" as a command inside the ShellCommand
but not on the bash command line.

Seems to have an impact on performance so relevant to gh-212.

spring-boot-cli/src/test/java/org/springframework/boot/cli/command/InitCommandTests.java

@@ -99,7 +99,7 @@ public class InitCommandTests {
 	@Test
 	public void runOptions() throws Exception {
 		SpringCli cli = new SpringCli();
-		InitCommand command = cli.getInitCommand();
+		InitCommand command = new InitCommand(cli);
 		command.run("src/test/resources/commands/options.groovy");
 		cli.find("foo").run("--foo=bar", "--bar=123");
 		assertTrue(this.output.toString().contains("Hello Foo: bar=123"));

spring-boot-cli/src/test/java/org/springframework/boot/cli/command/ScriptCommandTests.java

@@ -44,7 +44,7 @@ public class ScriptCommandTests {
 	public void init() {
 		this.classLoader = Thread.currentThread().getContextClassLoader();
 		this.cli = new SpringCli();
-		this.init = this.cli.getInitCommand();
+		this.init = new InitCommand(this.cli);
 		executed = false;
 	}