Move inner classes out of Server.

This is only a move with appropriate code changes to use the new class
names. The only functional change was changing the visibility of
MethodDefinition's constructor to package-private so ServiceDefinition
could construct it.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=73569974
diff --git a/core/src/main/java/com/google/net/stubby/HandlerRegistry.java b/core/src/main/java/com/google/net/stubby/HandlerRegistry.java
index 33ad884..1a0db15 100644
--- a/core/src/main/java/com/google/net/stubby/HandlerRegistry.java
+++ b/core/src/main/java/com/google/net/stubby/HandlerRegistry.java
@@ -1,7 +1,7 @@
 package com.google.net.stubby;
 
-import com.google.net.stubby.Server.MethodDefinition;
-import com.google.net.stubby.Server.ServiceDefinition;
+import com.google.net.stubby.ServerMethodDefinition;
+import com.google.net.stubby.ServerServiceDefinition;
 
 import javax.annotation.Nullable;
 import javax.annotation.concurrent.ThreadSafe;
@@ -15,19 +15,19 @@
 
   /** A method definition and its parent's service definition. */
   public static final class Method {
-    private final ServiceDefinition serviceDef;
-    private final MethodDefinition methodDef;
+    private final ServerServiceDefinition serviceDef;
+    private final ServerMethodDefinition methodDef;
 
-    public Method(ServiceDefinition serviceDef, MethodDefinition methodDef) {
+    public Method(ServerServiceDefinition serviceDef, ServerMethodDefinition methodDef) {
       this.serviceDef = serviceDef;
       this.methodDef = methodDef;
     }
 
-    public ServiceDefinition getServiceDefinition() {
+    public ServerServiceDefinition getServiceDefinition() {
       return serviceDef;
     }
 
-    public MethodDefinition getMethodDefinition() {
+    public ServerMethodDefinition getMethodDefinition() {
       return methodDef;
     }
   }