Added support for "dub init" to take a list of dependencies. It will search...

... for the newest version numbers of each dependency on code.dlang.org (or whatever other PackageSupplier's are defined) and add the required string to dub.json.

The current <type> functionality (Where you can pass "vibe.d", "deimos" or "minimal" into dub init) has been moved to the --type=<type> option.
"minimal" is the default <type>, as is the case now.

Example:
dub init myProject vibe-d openssl logger --type=vibe.d
will produce dub.json:
{
	"name": "myproject",
	"description": "A simple vibe.d server application.",
	"copyright": "Copyright © 2014, Colin",
	"authors": ["Colin"],
	"dependencies": {
		"logger": "0.3.3",
		"vibe-d": "0.7.21-rc.4",
		"openssl": "1.1.3+1.0.1g"
	},
	"versions": ["VibeDefaultMain"]
}

That will fail for `dub init` because free_args is empty.
Use `if (free_args.length >= 1) dir = free_args[0];` instead.