separate manifest file from init one

this feature makes possible to include Phrasing js files without `jquery` and `jquery_ujs`
(when `jquery` and `jquery_ujs` already included in another manifest file)
this way seems as 
```
../javascripts/phrasing_init.js

//= require editor
//= require jquery.cookie
//= require phrasing_setup
```
and in view 
```
= javascript_include_tag :application
- if current_user.admin? # for example
  = javascript_include_tag 'phrasing_init`
```
I would rather transfer the editor file in the phrasing setup, since there is no use case to use it without phrasing.