rename tests -> api

Now that all the other tests are moved out of the tests directory
we can rename tests -> api to reflect that these tests are api
testing, and need to use only the internal clients.

Clean up references from other parts of OpenStack to the new api
namespace.

Reorder the imports as required with this naming change.

Added README.rst

Change-Id: I19203957f917b59e7c8a3838c590937752461a2f
diff --git a/tox.ini b/tox.ini
index 2449c86..066a2b5 100644
--- a/tox.ini
+++ b/tox.ini
@@ -20,7 +20,7 @@
          NOSE_OPENSTACK_SHOW_ELAPSED=1
          NOSE_OPENSTACK_STDOUT=1
 commands =
-  nosetests --logging-format '%(asctime)-15s %(message)s' --with-xunit --xunit-file=nosetests-full.xml -sv tempest/tests tempest/scenario tempest/thirdparty tempest/cli
+  nosetests --logging-format '%(asctime)-15s %(message)s' --with-xunit --xunit-file=nosetests-full.xml -sv tempest/api tempest/scenario tempest/thirdparty tempest/cli
 
 [testenv:smoke]
 sitepackages = True
@@ -46,7 +46,7 @@
          NOSE_OPENSTACK_STDOUT=1
 commands =
    python -m tools/tempest_coverage -c start --combine
-   nosetests --logging-format '%(asctime)-15s %(message)s' --with-xunit --xunit-file=nosetests-full.xml -sv tempest/tests tempest/scenario tempest/thirdparty tempest/cli
+   nosetests --logging-format '%(asctime)-15s %(message)s' --with-xunit --xunit-file=nosetests-full.xml -sv tempest/api tempest/scenario tempest/thirdparty tempest/cli
    python -m tools/tempest_coverage -c report --html
 
 [testenv:pep8]