Fix wrong doc string for meter type

Meter type can be (gauge, delta, cumulative), not (gauge, counter).
This patch also fixes a typo s/extention/extension/.

Change-Id: I11d7fcefe0ec40afbf9ecc976cb65752600ea1c0

ceilometer/storage/impl_log.py

@@ -115,7 +115,7 @@ class Connection(base.Connection):
         """Return an iterable of dictionaries containing meter information.
 
         { 'name': name of the meter,
-          'type': type of the meter (guage, counter),
+          'type': type of the meter (gauge, delta, cumulative),
           'resource_id': UUID of the resource,
           'project_id': UUID of project owning the resource,
           'user_id': UUID of user owning the resource,

ceilometer/storage/models.py

@@ -171,7 +171,7 @@ class Meter(Model):
         """Create a new meter.
 
         :param name: name of the meter
-        :param type: type of the meter (guage, counter)
+        :param type: type of the meter (gauge, delta, cumulative)
         :param unit: unit of the meter
         :param resource_id: UUID of the resource
         :param project_id: UUID of project owning the resource

ceilometer/tests/alarm/test_singleton_alarm_svc.py

@@ -71,7 +71,7 @@ class TestSingletonAlarmService(test.BaseTestCase):
             self.singleton._evaluate_assigned_alarms()
             self.threshold_eval.evaluate.assert_called_once_with(alarm)
 
-    def test_unknown_extention_skipped(self):
+    def test_unknown_extension_skipped(self):
         alarms = [
             mock.Mock(type='not_existing_type'),
             mock.Mock(type='threshold')