Support ~ with the j command.

Shortly after installing Jump-Location, I realized that I couldn't fully replace my `cd` usage with `j` because I often use `cd ~`. 

To resolve this, I've changed the j alias to instead be a function, so that I can call `Resolve-Path` if the path is an actual path instead of a shortcut. This way, commands like `j ~` will work.

One drawback to what I've currently got is that only the alias supports this - I'd have to change the actual Set-JumpLocation command otherwise. I didn't know if it was worth it for that or not.

I'm open to thoughts, criticisms, etc. Thanks so much!