NSURL integration, bug fix

- My image was somehow deleted from my ‘Assets’ folder, so I’ve found
the image again then decided to simply add it to the application at
500x500 resolution instead of 500x333, as it used to be.

- I’ve also fixed a bug where my ‘Apartment Paris’ window was starting
completely off of the screen, and a few others.

The main reason I’m making this commit is because I’ve learned to use
NSURL to fetch files from the Internet! That’s very exciting and it
opens many doors for Objective-C developers.