Revert "use gfm"

This reverts commit 059836b4227d5f465a1136c1b1c9543578aa1f66.

Conflicts:
	spec/support/has_markdownable_tests.rb
Revert "refactor"

This reverts commit eb110fb5ddc0dc7f2692e1da9666f3d41b9c8a15.
Revert "add test"

This reverts commit f1b4f58db697d6a07af1a59ba402249719e5f2f3.

Conflicts:
	spec/models/article_spec.rb
Revert "fix compilation ruby version"

This reverts commit e4c164267d9084458088c638fcc5be469d19311b.
Revert "delete .keep"

This reverts commit 70e90c0cda2904816ce10ce682aeaea52a2820a7.
Revert "fix MarkdownPreview"

This reverts commit b1611a4a9453c8d272f0577ae01e13a9b6b6f5aa.
Revert "refactor markdown"

This reverts commit 6967a32d957aaa3a0c97a5417090a6707cd49e13.

Conflicts:
	app/models/article.rb
Fix some configuration files.
Fix invalid test.
Fix version of the sass-rails.
Merge pull request #126 from lodge/revert-gfm

Revert gfm