Allow passing environent variables to StreamProcessors

Add support for an 'env' field to the StreamProcessor configuration
and append the environment variables found there to the os.Environ()
array.
The env field takes environment variables in the form of key=value.

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>

services/server/server.go

@@ -91,7 +91,7 @@ func New(ctx context.Context, config *srvconfig.Config) (*Server, error) {
 		return nil, err
 	}
 	for id, p := range config.StreamProcessors {
-		diff.RegisterProcessor(diff.BinaryHandler(id, p.Returns, p.Accepts, p.Path, p.Args))
+		diff.RegisterProcessor(diff.BinaryHandler(id, p.Returns, p.Accepts, p.Path, p.Args, p.Env))
 	}
 
 	serverOpts := []grpc.ServerOption{