(Features) Display more precise model details (e.g. MacBook Pro (15-inch, Mid 2010))

Hello again,

Here's one of the feature requests from `README.md`.  I went to the Apple website and made a list of all of the common MacBook Pro, MacBook Air, and iMac models and made this into Models.txt. Using a bit of `grep` and `sed` magic, OSXey pulls the model name out of the file and into the display. The install script is modified to copy Models.txt into and out of /usr/local/bin/.