i18n js - AMD support

This is a patch for #22403

I have been having problems integrating the javascript i18n support with a complex javascript front-end. It would be tremendously useful for the global 'django' object - that is exported in 'django/views/i18n.py' - to also be exported as an AMD module. 

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I also fixed some small linting error. In javascript it is better to use strict comparison with triple equals.