I currently own an iMac and a rMBP. I am wanting to sell the iMac however. I do not currently own an external hard drive however I do plan to buy one in the near future. In the mean time I'd like to move everything over from my iMac's hard drive to my MBP's SSD. My question is, what is the best way to get my iTunes library/backups fully moved over so they can be sync'd with my mobile devices?