[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=XWALK-1989
BUG=XWALK-1658

Note: updateBatch method is still not done so the above bug is only partially fixed. 
sorry that missed this one last round, `editableAttributes()` -> ``editable_attributes()`