javadoc-ify akka-actor

Conflicts:
	project/AkkaBuild.scala
add javadoc to most projects

Conflicts:
	project/AkkaBuild.scala
build unified javadocs (under target/genjavadoc-api), see #3122

this also changes the akka_*-javadoc.jar to contain the assembled
javadocs

Conflicts:
	project/AkkaBuild.scala
fix formatting of Java API in doc comments + genjavadoc 0.3

Conflicts:
	akka-actor/src/main/scala/akka/io/UdpConn.scala
	akka-actor/src/main/scala/akka/io/UdpFF.scala
	akka-actor/src/main/scala/akka/japi/JavaAPI.scala
	akka-actor/src/main/scala/akka/pattern/CircuitBreaker.scala
	akka-actor/src/main/scala/akka/routing/Routing.scala
	akka-actor/src/main/scala/akka/serialization/Serializer.scala
	akka-actor/src/main/scala/akka/util/ByteString.scala
	akka-agent/src/main/scala/akka/agent/Agent.scala
	akka-zeromq/src/main/scala/akka/zeromq/SocketOption.scala
Clean up erroneous MiMa settings in the build.
genjavadoc is now off by default, see #3141

but it complains if you then try to build the docs
Clean up erroneously merged sub-project
update to genjavadoc 0.4 and fix path concat in Unidoc, see #3144
Merge pull request #1249 from akka/wip-3145-enable-javadoc-generation-ban

#3145 enable javadoc generation for 2.1.x