heat tests change project_dir path

By default, heat-tests sets project dir to
/usr/<lib/lib64>/python2.7/site-packages/.  However
all heat config files are within /etc/heat.  So
set project_dir to "/"

Signed-off-by: Vu Tran <vu.tran@windriver.com>

diff --git a/heat/tests/common.py b/heat/tests/common.py
index ea5df9a..2bdc231 100644
--- a/heat/tests/common.py
+++ b/heat/tests/common.py
@@ -42,7 +42,8 @@ class HeatTestCase(testtools.TestCase):
         self.addCleanup(enable_sleep)
 
         mod_dir = os.path.dirname(sys.modules[__name__].__file__)
-        project_dir = os.path.abspath(os.path.join(mod_dir, '../../'))
+        #project_dir = os.path.abspath(os.path.join(mod_dir, '../../'))
+        project_dir = "/"
         env_dir = os.path.join(project_dir, 'etc', 'heat',
                                'environment.d')