Added javadocs and separated trivial implementations into distinct packages.
diff --git a/core/trivial/src/main/javadoc/org/onlab/onos/net/trivial/host/impl/package.html b/core/trivial/src/main/javadoc/org/onlab/onos/net/trivial/host/impl/package.html
new file mode 100644
index 0000000..79f7bb0
--- /dev/null
+++ b/core/trivial/src/main/javadoc/org/onlab/onos/net/trivial/host/impl/package.html
@@ -0,0 +1,3 @@
+<body>
+Core subsystem for tracking edn-station hosts.
+</body>
\ No newline at end of file