Revert proto defs to 0.0.4

Author: Dave Syer

pom.xml

@@ -59,7 +59,7 @@
 		<dependency>
 			<groupId>io.projectriff</groupId>
 			<artifactId>riff-function-proto</artifactId>
-			<version>0.0.6-SNAPSHOT</version>
+			<version>0.0.4</version>
 		</dependency>
 		<dependency>
 			<groupId>io.grpc</groupId>