Rails4 assets

Changes to get asset pipeline working for rails4. Some of the velocity pages do not look pretty, but getting some help from @ermauliks to get them fixed. More pull requests to come soon.
How about
```ruby
ruby = File.expand_path(File.join("..", "..", "tools", "bin", __FILE__, (Gem.win_platform? ? "go.jruby.bat" : "go.jruby")))
```
Because, in case of Windows, we should be using ```\``` instead of ```/```