Initial commit based on current tempest

This creates the tempest plugin for horizon and duplicates
the existing horizon scenario test in tempest.

Change-Id: I9430b6cefc884ecc105e91ec19a07987aa70ef98
diff --git a/doc/source/contributing.rst b/doc/source/contributing.rst
new file mode 100644
index 0000000..1728a61
--- /dev/null
+++ b/doc/source/contributing.rst
@@ -0,0 +1,4 @@
+============
+Contributing
+============
+.. include:: ../../CONTRIBUTING.rst