Do not use suppport message if it's None

'message' attribute of SupportStatus class has default value equal None.
If you use support_status value in Schema class without providing
'message', you will get in documentation warning in form: DEPRECATED - None.
It looks confused and in such case we should display only 'status'
attribute: DEPRECATED.

Change-Id: I482fe6a9ca134e9e3bc54282b4b10ed98c29b028
Merge "Do not use suppport message if it's None"