Update grit for ruby 2.0 support

Gemfile

@@ -22,7 +22,7 @@ gem 'omniauth-twitter'
 gem 'omniauth-github'
 # GITLAB patched libs
-gem "grit",          git: "https://github.com/gitlabhq/grit.git",           ref: '7f35cb98ff17d534a07e3ce6ec3d580f67402837'
+gem "grit",          git: "https://github.com/gitlabhq/grit.git",           ref: '09918a3f3217eab7d3b6f5936d5ea2a07f886794'
 gem 'grack',         git: "https://github.com/gitlabhq/grack.git",          ref: 'ba46f3b0845c6a09d488ae6abdce6ede37e227e8'
 gem 'grit_ext',      git: "https://github.com/gitlabhq/grit_ext.git",       ref: '8e6afc2da821354774aa4d1ee8a1aa2082f84a3e'

Gemfile.lock

@@ -23,8 +23,8 @@ GIT
 GIT
   remote: https://github.com/gitlabhq/grit.git
-  revision: 7f35cb98ff17d534a07e3ce6ec3d580f67402837
-  ref: 7f35cb98ff17d534a07e3ce6ec3d580f67402837
+  revision: 09918a3f3217eab7d3b6f5936d5ea2a07f886794
+  ref: 09918a3f3217eab7d3b6f5936d5ea2a07f886794
   specs:
     grit (2.5.0)
       diff-lcs (~> 1.1)