website: fix middleman-gh-page build on a repo subdir

www/Gemfile

@@ -22,4 +22,4 @@ gem 'slim'
 gem 'font-awesome-middleman'
 
 # Handle GitHub pages deployment
-gem 'middleman-gh-pages'
+gem 'middleman-gh-pages', github: 'elthariel/middleman-gh-pages'

www/Gemfile.lock

@@ -1,3 +1,10 @@
+GIT
+  remote: git://github.com/elthariel/middleman-gh-pages.git
+  revision: 7f70eaa27ff670f668b423620c14d19f059c7768
+  specs:
+    middleman-gh-pages (0.0.3)
+      rake (> 0.9.3)
+
 GEM
   remote: http://rubygems.org/
   specs:
@@ -68,8 +75,6 @@ GEM
       rack-test (~> 0.6.2)
       thor (>= 0.15.2, < 2.0)
       tilt (~> 1.4.1, < 2.0)
-    middleman-gh-pages (0.0.3)
-      rake (> 0.9.3)
     middleman-livereload (3.1.1)
       em-websocket (>= 0.2.0)
       middleman-core (>= 3.0.2)
@@ -132,7 +137,7 @@ DEPENDENCIES
   font-awesome-middleman
   jquery-middleman
   middleman (~> 3.3.3)
-  middleman-gh-pages
+  middleman-gh-pages!
   middleman-livereload (~> 3.1.0)
   slim
   tzinfo-data

www/Rakefile

@@ -1 +1,3 @@
+PROJECT_ROOT = `git rev-parse --show-toplevel`.strip + '/www'
+
 require 'middleman-gh-pages'