Apply monkeypatching from eventlet before the tests starts

This should prevent issues with classes which may not have been
otherwise instrumented (and sahara_engine and sahara_all do the
instrumentation at the beginning anyway).

Issues have been notices with eventlet 0.20.1 which now instruments
subprocess.

Change-Id: I17adb877483dbf0b0aa559029c61715d1cef9d7b

sahara/tests/__init__.py

@@ -13,6 +13,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from sahara.utils import patches
+patches.patch_all()
+
 import oslo_i18n
 
 # NOTE(slukjanov): i18n.enable_lazy() must be called before