Enable therubyracer JS env, reqd on linux

Gemfile

@@ -26,7 +26,7 @@ group :assets do
   gem 'coffee-rails', '~> 3.2.1'
 
   # See https://github.com/sstephenson/execjs#readme for more supported runtimes
-  # gem 'therubyracer'
+  gem 'therubyracer'
 
   gem 'uglifier', '>= 1.0.3'
 end

Gemfile.lock

@@ -129,6 +129,7 @@ GEM
       activesupport (>= 3.0.0)
       railties (>= 3.0.0)
     kgio (2.7.4)
+    libv8 (3.3.10.4)
     libwebsocket (0.1.3)
       addressable
     machinist (2.0)
@@ -279,6 +280,8 @@ GEM
       tilt (~> 1.1, != 1.3.0)
     state_machine (1.1.2)
     stringex (1.3.3)
+    therubyracer (0.10.1)
+      libv8 (~> 3.3.10)
     thor (0.14.6)
     tilt (1.3.3)
     treetop (1.4.10)
@@ -326,6 +329,7 @@ DEPENDENCIES
   spree_i18n!
   spree_skrill
   spree_usa_epay
+  therubyracer
   turn (~> 0.8.3)
   uglifier (>= 1.0.3)
   unicorn