Re-add hello.xml file (#147)

* Re-add hello.xml file

Apparently it was lost during the great refactoring.

* Remove hello.xml from test resources

proxy/src/main/java/google/registry/proxy/EppProtocolModule.java

@@ -134,7 +134,7 @@ public class EppProtocolModule {
   @Named("hello")
   static byte[] provideHelloBytes() {
     try {
-      return readResourceBytes(EppProtocolModule.class, "resources/hello.xml").read();
+      return readResourceBytes(EppProtocolModule.class, "hello.xml").read();
     } catch (IOException e) {
       throw new RuntimeException("Cannot read EPP <hello> message file.", e);
     }

proxy/src/main/resources/google/registry/proxy/hello.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
+  <hello/>
+</epp>