Adding Azure Cognitive Services as a provider

Overview

Azure's computer vision API. Docs

(+) Supports both tags and descriptions

Settings

ALT_GENERATOR_PROVIDER: 'wagtailaltgenerator.providers.cognitive.Cognitive'
COMPUTER_VISION_API_KEY: Azure Computer Vision API key
COMPUTER_VISION_REGION: The default region to use, e.g. westus, northeurope, etc