Add travis ci (#35)

* Add travis CI
* Add ci testing of example models (with python 2.7 as py3 still fails)
diff --git a/test/model/extensions/nodes/reclass.yml b/test/model/extensions/nodes/reclass.yml
new file mode 100644
index 0000000..94b7519
--- /dev/null
+++ b/test/model/extensions/nodes/reclass.yml
@@ -0,0 +1,3 @@
+
+classes:
+- third