Remove instructions about therubyracer for Linux

Instead of using therubyracerm, linux users should
`sudo apt-get install nodejs`, which hopefully will allow
Rails to find a node runtime.

Fixes railsbridge#339

Author: tjgrathwell

sites/en/installfest/create_a_rails_app.step

@@ -24,12 +24,6 @@ step "Create a new Rails app" do
 
   message "The command's output is voluminous, and will take some time to complete, with a long pause in the middle, after all the 'create...' statements ending in 'bundle install'.  When it fully completes, it will return you to your home prompt.  Look for the 'Your bundle is complete!' message just above."
 
-  tip do
-    message "On Linux, you may have to enable this line to your Gemfile:"
-    pre "gem 'therubyracer', :platforms => :ruby"
-    message "Just delete the '#' in front of the statement"
-  end
-
   console "cd test_app"
   console "rails server"
 

sites/en/installfest/linux.step

@@ -17,11 +17,11 @@ Open a terminal (Applications > Accessories > Terminal).  You may want to right-
     bison
     build-essential
     curl
-	git-core
-	libapr1
-	libaprutil1
-	libc6-dev
-	libltdl-dev
+    git-core
+    libapr1
+    libaprutil1
+    libc6-dev
+    libltdl-dev
     libreadline6
     libreadline6-dev
     libsqlite3-0
@@ -33,6 +33,7 @@ Open a terminal (Applications > Accessories > Terminal).  You may want to right-
     libxslt1-dev
     libyaml-dev
     ncurses-dev
+    nodejs
     openssl
     sqlite3
     zlib1g