Add support for Twitch

[gurupras]

Add support for all Twitch video types: video, channel and collection

Here's a demo

Sumary of proposed changes

• Adds new source file twitch.js under plugins
• Adds the 'twitch' provider

There's a few single-line changes in a bunch of files as part of adding Twitch as a new provider.

Task list

• Implement progressive enhancement
• Update readme.md with instructions on how to use Twitch
• Tested on supported browsers
• Gulp build completed

[gurupras]

I need help with progressive enhancement. I'm trying to get a sense of what this is right now, but currently, I have no idea on what it is or how it's implemented in the code.

[friday]

I need help with progressive enhancement. I'm trying to get a sense of what this is right now, but currently, I have no idea on what it is or how it's implemented in the code.

Progressive enhancement is similar to a "fallback", but instead of checking if the fallback is needed and applying it, you start with the fallback and add the improved behavior later when possible.

For Plyr, this means you add the provider's own embed code inside your custom element.

[MasterProvider]

@gurupras any update on this?