Add parameter to customize Qpid receiver capacity

[OpenStack Infra]

https://review.openstack.org/112536
commit 2464ca0b200ef01403aa3ceab52fae2fae521183
Author: Zhi Kun Liu <email address hidden>
Date: Thu Aug 7 17:34:17 2014 +0800

    Add parameter to customize Qpid receiver capacity

    In Qpid rpc backend, receiver capacity is 1 and is hardcoding.
    User can not customize it. This patch adds a parameter to make
    user can specify receiver capacity in conf file.

    - Reference about Receiver Capacity(Prefetch) from Qpid Doc
    By default, receiver requests the next message from the server
    in response to each fetch call, resulting in messages being
    sent to the receiver one at a time. As in the case of sending,
    it is often desirable to avoid this roundtrip for each message.
    This can be achieved by allowing the receiver to prefetch messages
    in anticipation of fetch calls being made. The receiver needs to
    be able to store these prefetched messages, the number it can hold
    is controlled by the receivers capacity.

    DocImpact

    Change-Id: I966b512aba6bdd8e9c5cf65cae01bfd21f04f330
    Closes-Bug: #1353914

[Tom Fifield (fifieldt)]

This will affect a number of tables as the new oslo.messaging is imported into the various projects.