Release 1.4.0
Merge pull request #1657 from mojombo/safe-whitelist

A gem-based plugin whitelist for `safe` mode
Update history to reflect merge of #1657
Don't check for >= 1.9 in Rakefile
Remove Ruby <1.9 core extensions
Remove checks for Ruby 1.8.x
Add tests in all the time that was omitted for Ruby 1.8.x
Remove File.read_with_options patch to allow 1.9 and 1.8 to behave the same
Move CSS files to includes.
Upgrade to normalize.css v2.1.3
Merge pull request #1787 from mojombo/css-includes-2

Move jekyllrb.com CSS to includes & Update Normalize.css to v2.1.3
Update history to reflect merge of #1787
Implement group_by Liquid filter & tests.
Mention the 'input' option to use a GFM parser in the kramdown options documentation.
in-progress patch for maruku and fenced code blocks
current state
move input GFM option down to the bottom, not in the defaults
Add link to Jekyll homepage
Update files list in gemspec.

Fixes #1793
Merge pull request #1791 from konklone/kramdown_gfm

Document Kramdown's GFM parser option