knife cookbook site vendor gives no indication of unmet dependencies

Knife cookbook site vendor provides an option to install a cookbook's dependencies, but it isn't terribly smart about it:

1. If you do specify to install deps, it blindly installs them without checking if you have any of them already
2. if you don't specify dependencies, it gives no warning about ones that might be missing

In my view, the best UX is to figure out which ones are needed, install them by default, and print a summary of what it installed at the end so the user knows which cookbooks to review. If this is not desirable because we want to be conservative about what code we download, then knife should figure out which deps are missing and issue a warning. In either case, the other behavior should be available with a command line switch (as it is now).