Support recursive tree output for --tasks

[sandipchitale]

Something like:

        function printTaskTree(tasks, taskKey, indent) {
            var taskObject;
            taskObject = tasks[taskKey];
            if (taskObject) {
                console.log(indent + (taskObject.name ? taskObject.name : taskKey));
                if (taskObject.dep) {
                    taskObject.dep.forEach(function(name) {
                        printTaskTree(tasks, name, indent + '  ');
                    });
                }
            }
        }

        printTaskTree(gulp.tasks, 'default', '');

[yocontra]

Send a PR?

[phated]

This can be done in userland with the exposed gulp.tree() method. Not likely to add this to the CLI

[phated]

As per #36 (comment), undertaker builds the recursive tree, it shouldn't be the responsibility of the taskTree method to do that.

[phated]

The test has been updated to be less confusing in 1c0da0d