[data processing] Make sahara service_type backwards compatible

[Lin Hua Cheng]

In kilo, the sahara service type was changed from data_processing to data-processing: https://github.com/openstack/horizon/commit/8c4a2cd1265c86d3493b82cb9d1277a2274f63cf

If a user is still in Juno, this would not be backwards compatible.

Add a fallback to check for "data_processing" when reading the service_catalog.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/165636

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/165636
Committed: https://git.openstack.org/cgit/openstack/horizon/commit/?id=54d4bf10f0e961dd408ebd42f571ede1da18c65f
Submitter: Jenkins
Branch: master

commit 54d4bf10f0e961dd408ebd42f571ede1da18c65f
Author: Ravi Repaka <email address hidden>
Date: Wed Mar 18 22:09:03 2015 +0000

    Add fallback on sahara endpoint lookup

    In Juno, sahara is registered as 'data_processing' in the catalog.

    When endpoint for 'data-processing' is not found in service catalog,
    fallback lookup to 'data_processing' to maintain backwards compatibility
    with Juno.

    Change-Id: I2c1e6342f21080d7209c584c91379b4d22c517a2
    Closes-Bug: #1433794