Add inline styling to front matter for post images

[caendesilva]

---
image: 
  path: cover.png
  style: 'max-height: 100px'
---

[caendesilva]

Should only be enabled in if 'allow_html' => true in config/markdown.php

[caendesilva]

I originally added this as a feature request because I wanted to set a max height to crop an image. I should just have cropped the image. There are very few reasons to use one-off inline styles. Modify your images beforehand, or publish the image.blade.php component to add custom classes. I considered adding a class property, but again, the point of the component is to have a consistent presentation, so why use a one-off style?