无法启动Rails服务器 - 无法找到JavaScript运行时

pallav@pallav-System-Product-Name:~/Workspace/blog$ rails server/home/pallav/.rvm/gems/ruby-2.0.0-p353/gems/execjs-2.0.2/lib/execjs/runtimes.rb:51:in `autodetect': Could not find a JavaScript runtime. See https://github.com/sstephenson/execjs for a list of available runtimes. (ExecJS::RuntimeUnavailable)  from /home/pallav/.rvm/gems/ruby-2.0.0-p353/gems/execjs-2.0.2/lib/execjs.rb:5:in `<module:ExecJS>'  from /home/pallav/.rvm/gems/ruby-2.0.0-p353/gems/execjs-2.0.2/lib/execjs.rb:4:in `<top (required)>'  from /home/pallav/.rvm/gems/ruby-2.0.0-p353/gems/uglifier-2.4.0/lib/uglifier.rb:3:in `require'  from /home/pallav/.rvm/gems/ruby-2.0.0-p353/gems/uglifier-2.4.0/lib/uglifier.rb:3:in `<top (required)>'  from /home/pallav/.rvm/gems/ruby-2.0.0-p353/gems/bundler-1.5.2/lib/bundler/runtime.rb:76:in `require'  from /home/pallav/.rvm/gems/ruby-2.0.0-p353/gems/bundler-1.5.2/lib/bundler/runtime.rb:76:in `block (2 levels) in require'  from /home/pallav/.rvm/gems/ruby-2.0.0-p353/gems/bundler-1.5.2/lib/bundler/runtime.rb:72:in `each'  from /home/pallav/.rvm/gems/ruby-2.0.0-p353/gems/bundler-1.5.2/lib/bundler/runtime.rb:72:in `block in require'  from /home/pallav/.rvm/gems/ruby-2.0.0-p353/gems/bundler-1.5.2/lib/bundler/runtime.rb:61:in `each'  from /home/pallav/.rvm/gems/ruby-2.0.0-p353/gems/bundler-1.5.2/lib/bundler/runtime.rb:61:in `require'  from /home/pallav/.rvm/gems/ruby-2.0.0-p353/gems/bundler-1.5.2/lib/bundler.rb:131:in `require'  from /home/pallav/Workspace/blog/config/application.rb:7:in `<top (required)>'  from /home/pallav/.rvm/gems/ruby-2.0.0-p353/gems/railties-4.0.2/lib/rails/commands.rb:74:in `require'  from /home/pallav/.rvm/gems/ruby-2.0.0-p353/gems/railties-4.0.2/lib/rails/commands.rb:74:in `block in <top (required)>'  from /home/pallav/.rvm/gems/ruby-2.0.0-p353/gems/railties-4.0.2/lib/rails/commands.rb:71:in `tap'  from /home/pallav/.rvm/gems/ruby-2.0.0-p353/gems/railties-4.0.2/lib/rails/commands.rb:71:in `<top (required)>'  from bin/rails:4:in `require'  from bin/rails:4:in `<main>'pallav@pallav-System-Product-Name:~/Workspace/blog$pallav@pallav-System-Product-Name:~/Workspace/b