Norton equivalent with dependent source

This is just a matter of references*.

When you start to tackle the problem you short circuit your port and draw a reference for the Norton current. It's just like saying "this is what positive Norton current is to me".

After solving the circuit you get a result that is negative? No problem: it just means that the current is actually flowing in the opposite way, i.e. out of node 1. Your answer and your book's are just the same: the book says that output current is positive, and gets a positive current that is then going out, while you say that input current is positive, and get a negative current that is then going out.

Note that an answer giving only the current would be incomplete: if I told you that the current flowing in the controlled source is 1A you should ask me: is it going from plus to minus or vice versa?

You can think of an analogy in kinematics: the first thing you do before solving a problem is choosing a reference system*. If you don't choose it and tell your teacher that the ball speed is 10m/s he should yell at you.

*I believe that's the correct English word, please comment if it's not.

The difference in the signs of the solutions lies in the directions chosen for the current. So, the answers are equivalent, the current is just flowing in the opposite direction to which you have selected.