remove the flask dependency when only V2 API in use

[Pádraig Brady]

Current flask is required even if only using V2 API

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/29370

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/29370
Committed: http://github.com/openstack/ceilometer/commit/e2c1de041ab8f1d3ce820c06875752ea46f13a97
Submitter: Jenkins
Branch: master

commit e2c1de041ab8f1d3ce820c06875752ea46f13a97
Author: Eoghan Glynn <email address hidden>
Date: Thu May 16 11:33:22 2013 +0000

    Allow suppression of v1 API.

    Fixes bug 1180567

    The v1 API is on the deprecation path, so should not require
    that distros have all its dependencies available.

    Thus we add a new configuration option to allow the v1 app
    creation to be suppressed.

    Change-Id: Ib5af241a57f54754be534c9acb92a377362571e3

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/grizzly
Review: https://review.openstack.org/31043