hypothesis: markdown and org-id arguments

[hwiorn]

• Convert Markdown format using Pandoc
• Add ID per annotation
• Add ID per page

Hypothesis uses Markdown syntax default. But hypothesis module handle the text as plain-text. I add --markdown options to the module for this.

And I want to link some org note to a heading of annotation using org-mode ID instead of file-based links. I have added a id-per-{annotation,page} option to make a hash UUID from their URL.