[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. 
Declare `id` as close as first use. And seems you only use `id` in one place, so I'd prefer 
```
    if (media_info_get_media_from_db(msg.get(STR_ID).to_str().c_str(),
                                     &handle)
        == MEDIA_CONTENT_ERROR_NONE) {
```