Allow classes to be namespaced with subdirectories

Classes files may now reside in subdirectories, which act as namespaces.
For instance, a class ``ssh.server`` will result in the class definition
to be read from ``ssh/server.yml``. Specifying just ``ssh`` will cause
the class data to be read from ``ssh/init.yml`` or ``ssh.yml``. Note,
however, that only one of those two may be present.

Signed-off-by: martin f. krafft <madduck@madduck.net>
diff --git a/examples/classes/node/unix.yml b/examples/classes/node/unix.yml
new file mode 100644
index 0000000..12bbac1
--- /dev/null
+++ b/examples/classes/node/unix.yml
@@ -0,0 +1,6 @@
+classes:
+  - node
+applications:
+  - motd
+parameters:
+  greeting: Hello, world!