Update description for image upload

[xiaohanyu]

The current description for /project/images_and_snapshots/->"Create An Image" is:

----
Description:

 Specify an image to upload to the Image Service.

 Currently only images available via an HTTP URL are supported. The image location must be accessible to the Image Service. Compressed image binaries are supported (.zip and .tar.gz.)

Please note: The Image Location field MUST be a valid and direct URL to the image binary. URLs that redirect or serve error pages will result in unusable images.
----

Since horizon support upload image from local file system, we should update the description.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/87624

[Openstack Gerrit (openstack-gerrit)]

Fix proposed to branch: master
Review: https://review.openstack.org/88389

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/87624
Committed: https://git.openstack.org/cgit/openstack/horizon/commit/?id=5e2adf12a927dd8b7d6783c147dc6853e6a4a18a
Submitter: Jenkins
Branch: master

commit 5e2adf12a927dd8b7d6783c147dc6853e6a4a18a
Author: Guillermo Cabrera <email address hidden>
Date: Tue Apr 15 09:54:25 2014 -0300

    updated description of the create image screen

    I update the current description on sceen
    /project/images ->"Create Image" that it said:
    -------
    Specify an image to upload to the Image Service.
    Currently only images available via an HTTP URL
    are supported. The image location must be accessible
    to the Image Service. Compressed image binaries are
    supported (.zip and .tar.gz.)

    Please note: The Image Location field MUST be a
    valid and direct URL to the image binary. URLs that
    redirect or serve error pages will result in unusable
    images.
    -------
    Since horizon supports upload image from local file
    system.
    Closes-Bug: #1254273

    Change-Id: I8bc706289f45f5f8c2db7ffa5e80b1f949a63867