Extend Functionality to Export the vars loaded from env.json into process.env Object ?

[nelsonic]

Hi @dshaw,
We would really like to extend _env_ to make all configuration loaded from env.json available as process.env.VAR_NAME would you accept a PR for this extension.
This would simply be a loop to itterate over the entries in env.json and add them to the process.env object using your env.set method.

(100% backward compatibility will be maintained and 100% test coverage)
Let us know.
Thanks!

[nelsonic]

Such that the following test will pass:

test('export env.json to process.env', function (t) {
  var env = require('..')(env_json)
  var keys = Object.keys(env);
  keys.map(function(k){
    t.equal(env[k], process.env[k])
  })
  t.end()
})