Support an alias for a bunch of annotations (line#1560)

Motivation:
A user may want to define his or her annotations as a custom annotation in order to apply the custom annotation to his or her annotated HTTP services. e.g:
```
// Define a custom annotation:
@ProducesJson
@LoggingDecorator
@interface MyApiSpecification {}

// Apply it to the annotated HTTP service:
@get("/api")
@MyApiSpecification
public Something getSomething() {}
```

Modifications:
- Add `AnnotationUtil` for finding a specific annotation or getting all annotations from an `AnnotatedElement`.
- Use `AnnotationUtil` instead of `ReflectionUtils.getAllAnnotations()`. The old one does not respect the order of the annotations because its return type is a `Set<Annotation>` (more specifically it's `HashSet`).

Result:
- Won't depend on the `ReflectionUtils`'s implementation when getting annotations.

NOTICE.txt

@@ -122,6 +122,11 @@ This product depends on Caffeine, distributed by Ben Manes:
   * License: licenses/LICENSE.caffeine.al20.txt (Apache License v2.0)
   * Homepage: https://github.com/ben-manes/caffeine
 
+This product depends on cglib, distributed by the cglib authors:
+
+  * License: licenses/LICENSE.cglib.al20.txt (Apache License v2.0)
+  * Homepage: https://github.com/cglib/cglib
+
 This product depends on completable-futures, distributed by Spotify AB:
 
   * License: license/LICENSE.completable-futures.al20.txt (Apache License v2.0)

core/build.gradle

@@ -1,4 +1,7 @@
 dependencies {
+    // cglib
+    testCompile 'cglib:cglib'
+
     // Caffeine
     compile 'com.github.ben-manes.caffeine:caffeine'
 

core/src/test/java/com/linecorp/armeria/internal/annotation/AnnotatedHttpServiceAnnotationAliasTest.java

@@ -0,0 +1,83 @@
+/*
+ * Copyright 2019 LINE Corporation
+ *
+ * LINE Corporation licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+package com.linecorp.armeria.internal.annotation;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+import javax.annotation.Nullable;
+
+import org.junit.ClassRule;
+import org.junit.Test;
+
+import com.linecorp.armeria.client.HttpClient;
+import com.linecorp.armeria.common.AggregatedHttpMessage;
+import com.linecorp.armeria.common.HttpData;
+import com.linecorp.armeria.common.HttpHeaders;
+import com.linecorp.armeria.common.HttpResponse;
+import com.linecorp.armeria.common.HttpStatus;
+import com.linecorp.armeria.common.MediaType;
+import com.linecorp.armeria.server.ServerBuilder;
+import com.linecorp.armeria.server.ServiceRequestContext;
+import com.linecorp.armeria.server.annotation.Get;
+import com.linecorp.armeria.server.annotation.Param;
+import com.linecorp.armeria.server.annotation.Produces;
+import com.linecorp.armeria.server.annotation.ResponseConverter;
+import com.linecorp.armeria.server.annotation.ResponseConverterFunction;
+import com.linecorp.armeria.testing.server.ServerRule;
+
+public class AnnotatedHttpServiceAnnotationAliasTest {
+
+    @Retention(RetentionPolicy.RUNTIME)
+    @ResponseConverter(MyResponseConverter.class)
+    @Produces("text/plain")
+    @interface MyResponse {}
+
+    static class MyResponseConverter implements ResponseConverterFunction {
+        @Override
+        public HttpResponse convertResponse(ServiceRequestContext ctx, HttpHeaders headers,
+                                            @Nullable Object result, HttpHeaders trailingHeaders)
+                throws Exception {
+            return HttpResponse.of(
+                    headers, HttpData.ofUtf8("Hello, %s!", result), trailingHeaders);
+        }
+    }
+
+    @ClassRule
+    public static ServerRule rule = new ServerRule() {
+        @Override
+        protected void configure(ServerBuilder sb) throws Exception {
+            sb.annotatedService(new Object() {
+                @Get("/hello/{name}")
+                @MyResponse
+                public String name(@Param String name) {
+                    return name;
+                }
+            });
+        }
+    };
+
+    @Test
+    public void serviceConfiguredWithAlias() {
+        final AggregatedHttpMessage msg = HttpClient.of(rule.uri("/")).get("/hello/Armeria")
+                                                    .aggregate().join();
+        assertThat(msg.status()).isEqualTo(HttpStatus.OK);
+        assertThat(msg.headers().contentType()).isEqualTo(MediaType.parse("text/plain"));
+        assertThat(msg.content().toStringUtf8()).isEqualTo("Hello, Armeria!");
+    }
+}

core/src/test/java/com/linecorp/armeria/internal/annotation/AnnotatedHttpServiceResponseConverterTest.java

@@ -365,7 +365,6 @@ public void cancel() {
 
     @Retention(RetentionPolicy.RUNTIME)
     @Target({ ElementType.TYPE, ElementType.METHOD })
-    @Produces("application/binary")
     @Produces("application/octet-stream")
     @interface UserProduceBinary {}