update immutable, draft-js, downgrade sass-loader

[bertyhell]

update immutable to avoid warnings:

immutable.js:4655 iterable.length has been deprecated, use iterable.size or iterable.count(). This warning will become a silent error in a future version. Error

Fixed in: https://github.com/immutable-js/immutable-js/releases/tag/v3.8.0

update draft-js to latest minor version

downgrade sass-loader otherwise i get errors when i try to run the project:

   ERROR in ./node_modules/braft-extensions/dist/emoticon.css (./node_modules/css-loader/dist/cjs.js!./node_modules/sass-loader/dist/cjs.js!./node_modules/braft-extensions/dist/emoticon.css)
    Module build failed (from ./node_modules/sass-loader/dist/cjs.js):
    TypeError: this.getResolve is not a function
        at Object.loader (C:\Users\bert\Documents\studiohyperdrive\repos\braft-editor\node_modules\sass-loader\dist\index.js:52:26)

install cross-env in dev dependencies since it is used to start the server in the npm scripts

Switch mergeclassnames dependency to install from github since that repository isn't published to the npm registry.

[benjaminnaesen]

Oh yes! I need this aswell! Thanks Bert! This is wreaking havoc in my braft instance.

[bertyhell]

@margox

Any chance you could merge this? The "immutable" issue is the biggest problem, since it causes thousands of warnings in the console, killing performance of the page.

If you don't have time, let me know, then i'll just "fork" and work off of that.

您是否有可能将其合并？ 不变的问题是最大的问题，因为它在控制台中引起成千上万的警告，从而破坏了页面的性能。

如果您没有时间，请告诉我，然后我会分岔努力。