OTS — Additional predefined PropertyGroupAttributes

In Section 2.2.5 of the specification, a number of pre-defined
PropertyGroupAttribute names and their associated values are described.
The following are also of value to better define the contract between
Activity service and PropertyGroup provider.

"marshal_response_update"
Indicates whether or not the PropertyGroupManager should be called when an
outbound response is marshalled. A value of "true" indicates that the
context for the managed PropertyGroup should be updated on a response. A
value of "false" indicates that the context for the managed PropertyGroup
is not updated on a response so the PropertyGroupManager is not called for
marshalResponse. The default value is "false" It may be preferable for
either a security or a performance point of view not to transmit server
context back to a client with a response.

"unmarshal_response_update"
Indicates whether or not the PropertyGroupManager should be called when an
inbound response is unmarshalled. A value of "true" indicates that the
context for the managed PropertyGroup should be updated by the response.
A value of "false" indicates that the context for the managed
PropertyGroup is not updated by the response so the PropertyGroupManager
is not called for unmarshalResponse. The default value is "false" It may
be preferable for either a security or a performance point of view not to
allow the local context to be updated by changes made in a downstream

Agree to the addition of more attributes.