Change show property values to be nullable.

- Do not update if new property values are null.
Update endpoint sources.

- Build from 2013-12-07 at 10:28:18 UTC.
Cloud show download and upload aware of null property values.

- Not updating local shows if a property value should ever be null.
Initial version of ShowTools, helps upload show prop changes.
Send favorite change in overview to cloud with ShowTools.