Use a markdown parser that supports GFM.
Merge branch 'markdown' of https://github.com/vole/vole into markdown

* 'markdown' of https://github.com/vole/vole:
  Comments.
  Functional 'load more' button.
  Update Changelog.
  Protect against empty posts. I think we need to check for whitespace in postBoxDisabled. But oh well.
  Allow submitting a post with ctrl + enter.
  Support past and future pagination.
  Backend support for pagination. Front-end support TODO.