major change for js and css structure, fix for all js issue

This is a major change
* Now on wards, we can put all our custom js in <b>application_js</b> folder
* All the plugins we can put in <b>plugin</b> folder. And you need to manually add that file to <b>application.js</b>. So that we can keep order of plugins.
* all custom css to application_css
* all plugin css to plugin folder. Here no need to manually add it
* all that js issue happened because of <b>turbolink</b> js. We can simply remove that js, that will solve all our issues. But I didn't removed it because that js is really good. It gives very good performance.
<br>
   <b>Notes about turbolink.js</b><br>
     # Now on wards don't use or wait for document ready call back. 
       Instead of using
<br>
      <code>$-></code> or <code>jQuery-></code> or <code> $(function(){});</code>
     use turbolink call back <code>$(document).on 'ready page:load', -></code>
    #if you want to avoid a particular link making a tubolink add <code>data-no-turbolink = "true"</code> to that link.
<br>
* don't add any js to dom directly. Add it <b>application.js</b> folder only. And validate existence of DOM element before using it. So there won't be any js crash.
   Note : you can validate existence of DOM element by
    eg: <code>
     $("#test").exists ->
        $(this).doWhateverStuffWithThis
</code>