Add a way to automatically update a package installed

[ninjamar]

Maybe store the URL of the package installed in a file, then run a command something like justupdate path/to/installation. This would find the corresponding URL of the package, then run justinstall.

[Explosion-Scratch]

The thing is is that this would require:

1. Keeping track of packages somewhere other than just the bin
2. Re-writing a lot of my messy code to be more organized and be able to install from a JSON entry
3. It brings up a lot of issues with installation, you can't assume that because installation with one binary name/url worked in the past it will again

Although, I've started a bit on this because it's a good idea — I likely won't get time to finish my branch but I'll push my changes in a min