Use dotenv variables to switch dev mode in grunt

[TiSiE]

Currently Grunt is called after npm install.
It is however unaware of the environment (development / test / production)
Because of this, even in development environments, all generated files will be 'uglified' by grunt - as it assumes production env.
We also define a grunt task alias for development environments omitting the 'uglification' of files.

We are using a dotenv file to set environment variables for the composer and php application.

There is a dotenv library available for nodes.

So the goal is to create a npm post-install script that calls grunt with environment specific tasks.