Implement oembed renders and improve quotes

client/stylesheets/base.less

client/views/app/message.coffee

packages/rocketchat-markdown/markdown.coffee

packages/rocketchat-oembed/client/baseWidget.coffee

packages/rocketchat-oembed/client/baseWidget.html

packages/rocketchat-oembed/client/oembedImageWidget.html

packages/rocketchat-oembed/client/oembedUrlWidget.coffee

packages/rocketchat-oembed/client/oembedUrlWidget.html

packages/rocketchat-oembed/client/oembedYoutubeWidget.coffee

packages/rocketchat-oembed/client/oembedYoutubeWidget.html

packages/rocketchat-oembed/package.js