ceilometer statistic print use less log

[ZhiQiang Fan]

when /v2/meters/foo/statistics is requested, the api process will print debug log:

computed value coming from u'(<ceilometer.storage.impl_mongodb.Connection object at 0x2b73146d4a90

this information actually provides nothing useful except the database type, but as an administrator, I already know the backend type, maybe the specific host id in a cluster is useful, but that is not easy to get from connection object

so I think this useless log should be removed

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/186658

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/186658
Committed: https://git.openstack.org/cgit/openstack/ceilometer/commit/?id=0d135b28d445b20ad12b170213401fc33b1c362e
Submitter: Jenkins
Branch: master

commit 0d135b28d445b20ad12b170213401fc33b1c362e
Author: ZhiQiang Fan <email address hidden>
Date: Fri May 29 14:27:46 2015 +0800

    remove useless log message

    When we calculate statistic data from database, we print a debug
    level log which says something like:

    computed value coming from u'(<ceilometer.storage.impl_mongodb.Connection
    object at 0x12345678>,)'

    This message only indicates which type of database we are using,
    nothing more. However the database type is specified by config file,
    so this log is actually redundant.

    Change-Id: Ia52f2d5f74509999097151e6906b4233214d74eb
    Closes-Bug: #1459911