Please support git dependencies

[tarot]

Git dependencies (like following) doesn't work due to missing prepack or prepare scripts.

"dependencies": {
    "react-lightning-design-system": "github:mashmatrix/react-lightning-design-system"
}

I think it is better to use prepare instead of prepublish.

[stomita]

@tarot I think the "prepare" script will not run when it is installed via npm install in other package. It should be "preinstall" to run correctly in the package install of depending project. Anyway the build will fail as it doesn't include devDependencies.

I'm against for building (=transpiling) scripts on demand because it forces to download many modules which is only required in building phase and not needed in runtime.

To refer the master or arbitrary branch on Github other than the published, we should consider including the built files in Git commit.