[Notes] Support markdown syntax

[san650]

As a reader I want to use markdown in my notes So I can highlight parts of the notes And have minimal formatting support

AC

• There's a button to display a preview of the note
• The note shows the html version of the markdown in the display view
• The note shows the markdown in the edit view

[hidnasio]

This task is deprecated. Markdown is already implemented and I added a new task for the preview functionality.

[san650]

Actually, this is part of the Notes feature, which allows to add notes (comments) to a resource.

The idea is to append notes in a given resource.