Enhances client to support unique meter retrieval

[OpenStack Infra]

https://review.openstack.org/272633
Dear bug triager. This bug was created since a commit was marked with DOCIMPACT.
Your project "openstack/python-ceilometerclient" is set up so that we directly report the documentation bugs against it. If this needs changing, the docimpact-group option needs to be added for the project. You can ask the OpenStack infra team (#openstack-infra on freenode) for help if you need to.

commit c45000c7594ad6fbfabf44c0615dce3021f43605
Author: Rohit Jaiswal <email address hidden>
Date: Tue Jan 26 08:36:43 2016 -0800

    Enhances client to support unique meter retrieval

    meter list API is enhanced to support a unique param
    If specified as True, it returns a unique list of
    meters.

    This patch enhances the ceilometer-client to support
    the unique argument in the shell and the client bindings.

    DocImpact
    Closes-Bug: #1506959

    Change-Id: I011ca725c25e1cdbe9891c3719f13f5cd34142ea