First release of Mastodon Share Button

MSB is now usable to use on your website.
This script use Javascript ES5 and does not work on Internet Explorer.
It also use cookie to save the user's instance and reuse the cookie to share your button's data on Mastodon.

This release is the first one and it will be the base of the future of MSB. Then, don't hesitate to send your opinion or share your ideas.

Don't forget to read README.md to use MSB as indicated.