added close button on right hand side and buttons rearrangement for post form, comment button changes

Completed with : 
- [x] U.I. Changes
     - Added close button on right side of post form.
     - Rearrangement of preview, save as draft, publish,cancel button.
     - Cancel link changed to button.
     - Changes are made to the Comment button.

Can you please review the code changes? and let me know if any further modifications are required.

Thanks.