ENYO-2978: Designer undo/redo improvements

Related JIRA: https://enyojs.atlassian.net/browse/ENYO-2978

Limitations of go/return between Phobos and Deimos
(De)Activation of delete/undo/redo buttons of designer during undo/redo updates

Enyo-DCO-1.1-Signed-off-by: Vincent HERILIER vincent.herilier@hp.com