What to do if an advisor does not give enough time of his to you
In addition to dan's answer, I would add one practical piece of advice. Ask your mentor to schedule a 30-60 minute weekly meeting so that you can touch base regularly. I suggest asking in a way that puts the impetus on you (and not your mentor's lack of mentoring). For example, tell your mentor that you are having trouble developing your ideas efficiently and you're concerned about your progress through the program... and meeting weekly would help you stay on track. 

I don't get the sense that your mentor will be into this idea, but it's worth trying! This is what I did after my first year (I had a similar experience as you did). My mentor was receptive to the idea, and we've been meeting ever since. Good luck!