Adds Cinder client

This change adds Cinder client in services/volume

* Keeps existing tests for Compute Extensions in tempest/tests/compute
* Copies existing volumes test to tests/volume and refactors them to test the
Cinder API, and adds a BaseVolumesTest class
* Renames the Nova Extensions' volumes_client to volumes_extensions_client
* Adds build_interval and build_timeout parameters in config for Cinder
specific tests
* Renames build_interval and build_timeout environment variables in the
Devstack template file to COMPUTE_BUILD_INTERVAL and COMPUTE_BUILD_TIMEOUT
* Adds volume specific environment variables VOLUME_BUILD_INTERVAL AND
VOLUME_BUILD_TIMEOUT to the Devstack template file.

Fixes LP Bug #1026190

Change-Id: I14d980ada1ddb29e8147f990aaf239fdcaae5eb6
diff --git a/tempest/tests/compute/base.py b/tempest/tests/compute/base.py
index 5e6eb7d..84269d6 100644
--- a/tempest/tests/compute/base.py
+++ b/tempest/tests/compute/base.py
@@ -17,6 +17,7 @@
 
 import logging
 import time
+import nose
 
 import unittest2 as unittest
 
@@ -60,6 +61,7 @@
         cls.security_groups_client = os.security_groups_client
         cls.console_outputs_client = os.console_outputs_client
         cls.limits_client = os.limits_client
+        cls.volumes_extensions_client = os.volumes_extensions_client
         cls.volumes_client = os.volumes_client
         cls.build_interval = cls.config.compute.build_interval
         cls.build_timeout = cls.config.compute.build_timeout