Updating deps.  Notable changes:

chunky_png:
* Fixed an error n 4-bit resampling code.

fast-stemmer:
* Fixed to work with compilers other than gcc.

fssm:
* Remove deprecation message.
* Fix to work with JRuby.

haml:
* Fix for line numbers reported from exceptions in nested blocks.

kramdown:
* BREAKING CHANGE: Code language is now specified via .language-CODELANG instead of lang='CODELANG'
  * See this page for explanation: http://kramdown.rubyforge.org/news.html
Merge branch 'update_dependencies' into integration
Merge pull request #1051 from MrJoy/patches_from_master

Bring over a couple little things from master...
Merge pull request #1047 from MrJoy/remove_redundant_require

Remove redundant require statement from Rakefile.
Merge pull request #1043 from MrJoy/gitignore_cleanup

Ignore all generated JS bundles, preview-mode flag, generated _config.yml, and most editor temp files.
Merge pull request #1042 from MrJoy/fix_compass_integration

Fix static reference to instance method in Compass' config.
Allow .md for markdown files.
Merge branch '2.1' into integration
Merge branch 'allow_short_markdown_extension_redux' into integration