#437 - Move execution for IIFE to index.js

[woodcockjosh]

By moving the execution of the IIFE to index.js it allows me to bypass the globally created instance of i18n in order to preserve the context between applications.

This change allows me to import i18n function like this

const i18nFn = require('i18n/i18n');

const i18nInstance = new i18nFn();

i18nInstance.configure({});

Which is a solution for #437

rather than

const i18n = require('i18n');

i18n.configure({});

So that the subsequent calls to configure do not overwrite the preceding calls to configure

[coveralls]

Coverage increased (+0.004%) to 97.778% when pulling 9674bc2 on woodcockjosh:master into fb9aa22 on mashpie:master.

[coveralls]

Coverage decreased (-96.6%) to 1.215% when pulling 3c9979d on woodcockjosh:master into fb9aa22 on mashpie:master.

[woodcockjosh]

Possible dupe of #329

[mashpie]

feature is released as of 0.12.0 with some extra sugar (shortcut to i18n.configure on creation):

const { I18n } = require("i18n");

const i18n = new I18n({
    locales:['en', 'de'],
    directory: __dirname + '/locales'
});

see https://github.com/mashpie/i18n-node/tree/master#as-instance for details