Comment 2 for bug 1212159

Reviewed: https://review.openstack.org/41926
Committed: http://github.com/openstack/ceilometer/commit/a6ca935665aef3cf00b8a01ca8d4fb4becf1051f
Submitter: Jenkins
Branch: master

commit a6ca935665aef3cf00b8a01ca8d4fb4becf1051f
Author: Fei Long Wang <email address hidden>
Date: Wed Aug 14 21:40:57 2013 +0800

    Raise error when period with negative value

    Based on current implement, when use launch below REST API:
    GET http://10.1.0.175:8777/v2/meters/port/statistics?period=-1
    The result will be 200 OK. No any error reports. This query
    should not allow negative value setting but 400 error, and
    prompts like this: "Period must be positive.". Just like
    setting "Limit" to negative.

    Fixes bug 1212159

    Change-Id: I8d547fdf8faae2094b24c81da6b233b432bc99ae