Meteor: how to add packages manually using smart.json

I just tried to add packages to my meteor project using smart.json like this:

{
    "packages": {
    "scss": {},
    "iron-router": {},
    "normalize.css": {
        "git": "https://github.com/rithis/meteor-normalize.css"
    },
    "Meteor.cron": {
        "git": "https://github.com/alexsuslov/Meteor.cron"
    }
}

In this case I've manually added normalize.css and Meteor.cron. Now when I do

$> mrt update

These packages are installed into the packages directory. So far no problems, but I don't think they are used. I didn't see a normalize.css in my browser and to test for Meteor.cron I added a test file in the server directory with

console.log(Meteor.Cron)

which prints undefined Any suggestions what I'm doing wrong here ?

you are using incorrect git clone URLs. try this in your smart.json

{
    "packages": {
    "scss": {},
    "iron-router": {},
    "normalize.css": {
        "git": "https://github.com/rithis-archive/meteor-normalize.css.git"
    },
    "Meteor.cron": {
        "git": "https://github.com/alexsuslov/Meteor.cron.git"
    }
}