Support for templating fields within style attributes

[nick-avi-say]

Hi, currently when using variables in fields. The render method strips out the value. Tried setting validation to skip, and that alleviates the error thrown, but the string "{{myVariable}}" is still stripped

<MjmlBody backgroundColor="{{myVariable}}">

[nick-avi-say]

PR created here https://github.com/wix-incubator/mjml-react/pull/74

[daliusd]

This project is not maintained anymore so there will be no fix proposal.