[new] Add twemoji from Twitter (1.1.1)

Source: https://github.com/twitter/twemoji

This is Twitter's library to support standard Unicode emoji support across all platforms.
There are 800+ emojis, in 2 image formats (png, svg), with PNGs in 3 sizes (16x16, 36x36, 72x72). Because of this, there are a lot of new files in the PR.

autoupdate from git is configured in package.json.