[DOC BLD FIX] Correct reST field lists in docstrings

Most common format for documenting arguments is reST field, the incorrect
docstring will cause a Sphinx warning to be generated and caused the documentation
to be improperly rendered.

[1] http://sphinx-doc.org/domains.html#info-field-lists

Change-Id: I031cc3ca202b140b6ff6d9fadc46e0765ee2f36c
diff --git a/tempest/lib/common/rest_client.py b/tempest/lib/common/rest_client.py
index 63cf07f..f58d737 100644
--- a/tempest/lib/common/rest_client.py
+++ b/tempest/lib/common/rest_client.py
@@ -371,7 +371,7 @@
         on the endpoint in the catalog will return a list of supported API
         versions.
 
-        :return tuple with response headers and list of version numbers
+        :return: tuple with response headers and list of version numbers
         :rtype: tuple
         """
         resp, body = self.get('')
diff --git a/tempest/lib/services/clients.py b/tempest/lib/services/clients.py
index cd3bab0..5f230b7 100644
--- a/tempest/lib/services/clients.py
+++ b/tempest/lib/services/clients.py
@@ -161,7 +161,7 @@
         :param kwargs: Parameters to be passed to all clients. Parameters
             values can be overwritten when clients are initialised, but
             parameters cannot be deleted.
-        :raise ImportError if the specified module_path cannot be imported
+        :raise ImportError: if the specified module_path cannot be imported
 
         Example::