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