[Content] Support for update methods and editable attributes

The content api has editableAttributes array which lists the attributes that can be updated via update method.

Editable attributes are non-readonly attributes in the spec (name, description, orientation, geolocation, rating)

Geolocation requires tizen.SimpleCoordinates() which is added to the Tizen API.

Also some typo fixes.

TCT pass rate: +12% (62->74)

BUG=XWALK1989

Note: updateBatch method is still not done so the above bug is only partially fixed. 
Well, All the other constructors in the file are defined this way including the comment. I'd like to keep it for consistency and remove them all (later) if that is the style.