Fix a bug where meta data was read from the content

Signed-off-by: Dries Vints <dries.vints@gmail.com>
Merge pull request #2 from DriesForks/bugfix/fix-meta-data-bug

Fix a bug where meta data was read from the content
Allow for extra Markdown features

This allows for fenced code blocks, footnotes, etc.
Switch from private to protected properties

So developers can extend the class.
Merge pull request #4 from DriesForks/fix/switch-private-to-protected-properties

Switch from private to protected properties
Merge pull request #3 from DriesForks/feature/extra-parser

Allow for extra Markdown features