Prevent JLine from expanding !history events

We might also want to rethink "!" as a shell exec command (since it means
something in a real shell and in JLine). E.g. use "exec" or something.

Partial fix for gh-220 (ideally we'd process the events and catch
and handle exceptions).

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

@@ -105,6 +105,9 @@ public class ShellCommand extends AbstractCommand {
 		ConsoleReader reader = new ConsoleReader();
 		reader.addCompleter(new CommandCompleter(reader, this.springCli));
 		reader.setHistoryEnabled(true);
+		// Prevent exceptions if user types !foo. If anyone knows how to process those
+		// exceptions, please help out and write some code.
+		reader.setExpandEvents(false);
 		reader.setCompletionHandler(new CandidateListCompletionHandler());
 		return reader;
 	}