Introduce @EnableAsync

Introduce @EnableAsync#order

AsyncAnnotationBeanPostProcessor's 'order' property is now mutable;
@EnableAsync's 'order()' attribute allows for setting it, but must
have a default value, thus uses the new Ordered#NOT_ORDERED
constant - a reserved negative number very unlikely to be otherwise
used that may be interpreted as 'not ordered', useful in annotation
defaulting scenarios where null is not an option.

Introduce first working cut of AsyncConfiguration

Remove AsyncCapability

org.springframework.aspects/src/main/java/org/springframework/scheduling/aspectj/AspectJAsyncConfiguration.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2002-2011 the original author or authors.
+ *
+ * Licensed 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
+ *
+ *      http://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 org.springframework.scheduling.aspectj;
+
+import org.springframework.beans.factory.config.BeanDefinition;
+import org.springframework.context.annotation.AnnotationConfigUtils;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Role;
+import org.springframework.scheduling.annotation.AbstractAsyncConfiguration;
+import org.springframework.scheduling.annotation.EnableAsync;
+
+/**
+ * Enables AspectJ-based asynchronous method execution.
+ *
+ * @author Chris Beams
+ * @since 3.1
+ * @see EnableAsync
+ * @see EnableAsync#mode
+ */
+@Configuration
+public class AspectJAsyncConfiguration extends AbstractAsyncConfiguration {
+
+	@Override
+	@Bean(name=AnnotationConfigUtils.ASYNC_EXECUTION_ASPECT_BEAN_NAME)
+	@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
+	public AnnotationAsyncExecutionAspect asyncAdvisor() {
+		AnnotationAsyncExecutionAspect asyncAspect = AnnotationAsyncExecutionAspect.aspectOf();
+		if (this.executor != null) {
+			asyncAspect.setExecutor(this.executor);
+		}
+		return asyncAspect;
+	}
+
+}