Bug 1042319 - [Gallery] Update gallery edit UI r=djf

I have been trying to incorporate editSettings= savedEditSetting or editSettings= clone(savedEditSetting), on cancel of edit tool.

The reason it's not working is direct copy of object changes the reference of editSettings object, making editSettings object different from reference object passed to ImageEditor in the constructor. 

https://github.com/mozilla-b2g/gaia/blob/master/apps/gallery/js/ImageEditor.js#L99
https://github.com/mozilla-b2g/gaia/blob/master/apps/gallery/js/ImageEditor.js#L494
https://github.com/mozilla-b2g/gaia/blob/master/apps/gallery/js/ImageEditor.js#L744

I have simplified code further by copying the properties e.g. editSettings.effect = savedEditSettings.effect instead of each individual value. 
The other workaround is to expose edits inside ImageEditor to be set again on Cancel like ImageEditor.edits = editSettings  which I am not sure is the best approach.