Update gem requirements to indicate node.js dependency.
Update gem requirements to indicate node.js dependency.

We explicitly use node.js for the r.js build; ExecJS can use runtimes
unsupported by r.js.

andrewtimberlake/requirejs-rails,sun16/requirejs-rails,jwhitley/requirejs-rails,skroutz/requirejs-rails,skroutz/requirejs-rails,getaroom/requirejs-rails,aar0nTw/requirejs-rails-sp,describeit/requirejs-rails,aar0nTw/requirejs-rails-sp,crashlytics/requirejs-rails,lsimoneau/requirejs-rails,MediaFactual/requirejs-rails,merqlove/requirejs-rails,merqlove/requirejs-rails,lsimoneau/requirejs-rails,andrewtimberlake/requirejs-rails,appfolio/requirejs-rails,appfolio/requirejs-rails,getaroom/requirejs-rails,getaroom/requirejs-rails,MediaFactual/requirejs-rails,sun16/requirejs-rails,andrewtimberlake/requirejs-rails,describeit/requirejs-rails,ipmobiletech/requirejs-rails,tributech/requirejs-rails,appfolio/requirejs-rails,airbnb/requirejs-rails,describeit/requirejs-rails,jwhitley/requirejs-rails,skroutz/requirejs-rails,ipmobiletech/requirejs-rails,describeit/requirejs-rails,tributech/requirejs-rails,MediaFactual/requirejs-rails,merqlove/requirejs-rails,jwhitley/requirejs-rails,andrewtimberlake/requirejs-rails,leppert/requirejs-rails,skroutz/requirejs-rails,bogwro/requirejs-rails,ipmobiletech/requirejs-rails,getaroom/requirejs-rails,crashlytics/requirejs-rails,MediaFactual/requirejs-rails,jwhitley/requirejs-rails,leppert/requirejs-rails,appfolio/requirejs-rails,bogwro/requirejs-rails,lsimoneau/requirejs-rails,airbnb/requirejs-rails,sun16/requirejs-rails,sun16/requirejs-rails,tributech/requirejs-rails,tributech/requirejs-rails,merqlove/requirejs-rails,lsimoneau/requirejs-rails,ipmobiletech/requirejs-rails