Remove not required packages in requirements.txt

[Wang Bo]

We need remove the not using packages in requirements.txt, Otherwise
the requirements.txt will be updated when global requirements updated unnecessarily.

Remove kombu since horizon never connect to message queue server.
Remove evenlet since horizon does not use evenlet to handle threading.

[Akihiro Motoki (amotoki)]

Is any review available on gerrit?
If you haven't uploaded a review, you don't need to set the status to 'In Progress' manually.

[Wang Bo (chestack)]

gerrit link: https://review.openstack.org/#/c/260425/

I don't know why OpenStack Infra did not propose this link automaticlly

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/260425
Committed: https://git.openstack.org/cgit/openstack/horizon/commit/?id=0e5c978b94f0b6b0750be0685830765ab640c390
Submitter: Jenkins
Branch: master

commit 0e5c978b94f0b6b0750be0685830765ab640c390
Author: Bo Wang <email address hidden>
Date: Tue Dec 22 17:45:58 2015 +0800

    Remove not required packages in requirements.txt

    Remove the not using packages in requirements.txt, Otherwise
    the requirements.txt will be updated when global requirements updated.

    Change-Id: I9ec2dc52184e4454a42147a21673e30015bc6767
    Close-Bug: #1528777

[Rob Cresswell (robcresswell-deactivatedaccount)]

This patch addressed the bug: https://review.openstack.org/#/c/260425/