v4.2.1

Adds middleware that parses the X-Broker-API-Originating-Identity header and adds it as a value to the downstream context passed to the functions of the brokerapi.ServiceBroker interface. Thanks to @fitzoh.

This is added automatically as middleware if the brokerapi is constructed using brokerapi.New(). When using an existing gorilla.mux.Router via the brokerapi.AttachRoutes() function, you will have to attach this middleware manually if required.

Breaking Changes
This bumps the gorilla/mux dependency to v1.6.1+ to use the middleware functions.