more granular update_object publish

[mwfarb]

ATM we publish the entire object set of attributes even if we only update color. That can generate unnecessarily large messages. We should only publish what we need, but there are reasons we are doing it this way at the moment.

• We have a global sanity check for dashes (-) in attribute names, so we need to check the full object dict.
• We should extrapolate the above sanity check that can be called on a named-attribute basis to get this small-as-possible message update.

[EdwardLu2018]

Related: #103