Adds new v3 projects tests to Keystone

This submission adds a new test script "test_list_projects.py"
which has list projects with filters test cases. Also adds
missing v2 tests in v3 projects test script. Hence made
required changes in support functions too. As there is a new
script test_list_projects.py with list cases in it, hence removed
the test_list_projects test case from test_projects.py script and
added it to test_list_projects.py

Change-Id: I2db83e7cb70d89e7516c92eba4cb24115203e143
diff --git a/tempest/services/identity/v3/json/identity_client.py b/tempest/services/identity/v3/json/identity_client.py
index 8c72dfa..b389501 100644
--- a/tempest/services/identity/v3/json/identity_client.py
+++ b/tempest/services/identity/v3/json/identity_client.py
@@ -14,6 +14,7 @@
 #    under the License.
 
 import json
+import urllib
 
 from tempest.common import rest_client
 from tempest import config
@@ -120,8 +121,11 @@
         body = json.loads(body)
         return resp, body['project']
 
-    def list_projects(self):
-        resp, body = self.get("projects")
+    def list_projects(self, params=None):
+        url = "projects"
+        if params:
+            url += '?%s' % urllib.urlencode(params)
+        resp, body = self.get(url)
         self.expected_success(200, resp.status)
         body = json.loads(body)
         return resp, body['projects']