rename reva to proxy where applicable

proxy/pkg/config/config.go

@@ -84,12 +84,12 @@ type Reva struct {
 	Middleware Middleware
 }
 
-// Middleware configures reva middlewares.
+// Middleware configures proxy middlewares.
 type Middleware struct {
 	Auth Auth
 }
 
-// Auth configures reva http auth middleware.
+// Auth configures proxy http auth middleware.
 type Auth struct {
 	CredentialsByUserAgent map[string]string
 }