Add check of R library to guarantee package loads

Created by: johanneskoch94

Hey, so I'm 99% sure that a check for a "^00LOCK.*" folder is enough to figure out if a package is being updated. What I've implemented now is a bit heavy-handed, since as soon as any single package is being updated, all packages are loaded from the snapshot library. One could probably have something that only gets the package-being-updated from the snapshot, but oh well...

Do you think this is ok?