firebase-config v1.0.0
firebase-config: a command-line utility for working with firebase config files.
firebase-config is a utility that lets you manage different firebase config files for different environments. It uses the value of process.env.NODE_ENV to determine the appropriate firebase config file for that enviromnent and creates a firebase.json file that is a symlink to the firebase config file for that environment.
Installing globally:
Installation via npm.  If you don't have npm yet:
 curl https://npmjs.org/install.sh | shOnce you have npm:
 npm install firebase-config -gThis will install firebase-config globally so that it may be run from the command line.
Configuring with package.json:
firebase-config uses a special firebase-config field in the package.json to resolve locations of firebase config files.
For example,
"firebase-config": {
  "output": "public/",
  "configs": {
    "development": "config/firebase-dev.json",
    "production": "config/firebase-prod.json"
  }
}You can use the "output" field to tell firebase-config where to place the generated firebase.json file. This defaults to the directory containing package.json
The "configs" field is a map of values of NODE_ENV to the firebase config files to use for each environment.
Usage:
Set NODE_ENV
- linux & mac: export NODE_ENV=production
 - windows: set NODE_ENV=production
 
Run firebase-config from your project directory.
