Add NonSelectableProperties to SelectSupportType

1a. Add NonSelectableProperties to SelectSupportType in the capabilities spec: <Property Name= "NonSelectableProperties" Type= "Collection(Edm.PropertyPath)" Nullable= "false" >     <Annotation Term= "Core.Description" String= "These structural properties cannot be specified in a select statement." /> </Property>   1b. Alternatively, if we believe that read/write is a fundamental characteristic of the property, rather than a capability of the service, we could add a model annotation to the core vocabulary for specifying the readability/writeability of a property: <Term Name= "PropertyUsage" Type= "Core.PropertyUsageType" DefaultValue= "Create Read Update" Targets= "property" >     <Annotation Term= "Core.Description" String= "Specifies whether the target property is intended for use in a create, read, or update operation." /> </Term> <EnumType Name= "PropertyUsageType" IsFlags= "true" > <Member Name= "Create" Value=1>     <Annotation Term= "Core.Description" String= "The annotated property can be used in a Create operation." /> </Member> <Member Name= "Read" Value=2>     <Annotation Term= "Core.Description" String= "The annotated property can be read." /> </Member> <Member Name= "Update" Value=4>     <Annotation Term= "Core.Description" String= "The annotated value can be updated." /> </Member> </EnumType> 2. Add "Omitted" term to OData Core vocabulary used as an instance annotation to describe properties omitted from the payload: <Term Name= "Omitted" Type= "Edm.String" >     <Annotation Term= "Core.Description" String= "The annotated property in a request or response payload was omitted for the specified reason." /> </Term>