ENYO-2485: Add shorthand forms for Margin and Padding in css Style Editor

css Style Improvement:
1. dedicated drawers for margin and padding
* one for the shorthand, and, 
* one for the longhand form.

2. css Style editor layout
* drawers are closed except the first drawer which is background-style, on first access, and,
* drawers ares closed except the last modified, during the life time.

Tested: on mac using Chrome Version 28.0.1500.71

Enyo-DCO-1.1-Signed-off-by: Marie-Antoinette de Bonis-Hamelin (Marian)
marie-antoinette.de-bonis-hamelin@hp.com