mjml 2.0.0 on Node.js Yarn

Features

MJML is now a mono repo project with multiple packages
- mjml-core for the engine that renders MJML componenent
- mjml-cli for the cllient, based on mjml-core interface
- mjml is a standlone mjml client with standard MJML lib (column/section/body/...)
- One standalone package for each component
API te create a component is now much easier, and allow postRender hook with full HTML document. Document can be modified through cheerio
mjml root tag have been implemented #78 allows #157

<mjml>
  <mj-body>
    <mj-container>
      ...
    </mj-container>
  </mj-body>
</mjml>

Note that previous notation is deprecated but still available

<mj-body>
 ...
</mj-body>

.mjmlconfig allows you to define a list of included component that will be required by mjml-core

{
 "packages": [
    "mjml-body",
    "mjml-section" 
  ]
}

Fix #153 : comments inside a ending tags are back
align on column element is now a text-align on td
Remove min-width on a column for pixel layout. It will fix browser and Mail on iOS render
Fix when you use mjml React component with childrens