Generate -sources and -javadoc jars

Each spring-* subproject now has sourcesJar and javadocJar tasks

 - Ignore subproject overview.html files for now (not all have one)
 - Ensure @author attribution occurs
 - Javadoc 'header' is project description

spring-asm is a special case

 - source jar is created, but empty (to comply with entry rules for
   Maven Central)

 - add package-info.java explaining the nature of spring-asm
   this is nice, because it shows up in the public API docs now.

 - add SpringAsmInfo in the org.springframework.asm package as a
   placeholder allowing the generation of javadocs (see link to bug)

 - add explicit 'repackageAsm' Gradle task allowing for easy testing
   and merging of jar containing bundlor manifest as well as jar
   containing repackaged ASM classes.

org.springframework.asm/src/main/java/org/springframework/asm/SpringAsmInfo.java

@@ -0,0 +1,31 @@
+/*
+ * Copyright 2002-2012 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.asm;
+
+/**
+ * Placeholder to allow Javadoc generation. Required because
+ * <a href="http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4492654">this bug</a>
+ * does not allow the generation of Javadoc for packages having only a
+ * {@code package-info.java} file.
+ * <p>See <a href="package-summary.html">package-level Javadoc</a> for more
+ * information on {@code org.springframework.asm}.
+ *
+ * @author Chris Beams
+ * @since 3.2
+ */
+public final class SpringAsmInfo {
+}

org.springframework.asm/src/main/java/org/springframework/asm/package-info.java

@@ -0,0 +1,11 @@
+/**
+ * Spring's repackaging of {@code org.objectweb.asm.*} (for internal use only).
+ * <p>This repackaging technique avoids any potential conflicts with
+ * dependencies on ASM at the application level or from other third-party
+ * libraries and frameworks.
+ * <p>As this repackaging happens at the classfile level, sources and Javadoc
+ * are not available here. See the original ObjectWeb
+ * <a href="http://asm.ow2.org/asm223/javadoc/user">ASM 2.2.3 Javadoc</a>
+ * for details when working with these classes.
+ */
+package org.springframework.asm;