Add alarm severity in alarm-history output

Info about alarm's severity is missing from
the detail column for creation and deletion
type of alarm-history call.

This fix adds that.

Change-Id: I669126596ef7391530e7822c2807ffca7c6a1de1
Closes-Bug: 1468295

ceilometerclient/tests/unit/v2/test_shell.py

@@ -80,6 +80,7 @@ class ShellAlarmHistoryCommandTest(utils.BaseTestCase):
                    '"ok_actions": [], '
                    '"project_id": "57d04f24d0824b78b1ea9bcecedbda8f", '
                    '"type": "combination", '
+                   '"severity": "low", '
                    '"description": "Combined state of alarms '
                    '062cc907-3a9f-4867-ab3b-fa83212b39f7"}')
     ALARM_HISTORY = [{'on_behalf_of': '57d04f24d0824b78b1ea9bcecedbda8f',

ceilometerclient/v2/shell.py

@@ -353,7 +353,7 @@ def alarm_change_detail_formatter(change):
     if change.type == 'state transition':
         fields.append('state: %s' % detail['state'])
     elif change.type == 'creation' or change.type == 'deletion':
-        for k in ['name', 'description', 'type', 'rule']:
+        for k in ['name', 'description', 'type', 'rule', 'severity']:
             if k == 'rule':
                 fields.append('rule: %s' % _display_rule(detail['type'],
                                                          detail[k]))