Revert "Mark the sheepdog driver as unsupported"

Two issues described in the driver's comment are fixed or invalid:

* The CI issue is now fixed.

* I think there is no "license issues" because the "dog" command
  in Sheepdog, which is called by the Sheepdog driver, is executable,
  not library. So the driver has nothing to do with the paragraph
  "external libraries" in the OpenStack licensing requirements [1]
  even though Sheepdog is licensed under GPLv2.

[1] https://governance.openstack.org/tc/reference/licensing.html

This reverts commit eec8559ac9.

Change-Id: Ifec942ee8cdc21ff83a9b06dc03cf2dfb10a9443
Signed-off-by: Takashi Menjo <menjo.takashi@lab.ntt.co.jp>

cinder/volume/drivers/sheepdog.py

@@ -442,10 +442,6 @@ class SheepdogDriver(driver.VolumeDriver):
     # ThirdPartySystems wiki page
     CI_WIKI_NAME = "Cinder_Jenkins"
 
-    # TODO(smcginnis) Remove this driver in Pike if license issues are not
-    # resolved and third party CI requirements are not met
-    SUPPORTED = False
-
     def __init__(self, *args, **kwargs):
         super(SheepdogDriver, self).__init__(*args, **kwargs)
         self.configuration.append_config_values(sheepdog_opts)

releasenotes/notes/mark-sheepdog-unsupported-0d9e1310b8ae8dff.yaml

@@ -1,10 +0,0 @@
----
-upgrade:
-  - The Sheepdog driver has been marked as unsupported and is now
-    deprecated. enable_unsupported_driver will need to be set to
-    True in cinder.conf to continue to use it.
-deprecations:
-  - The Sheepdog driver has been marked unsupported and is now
-    deprecated. enable_unsupported_driver will need to be set to
-    True in cinder.conf to continue to use it. It is planned to be
-    removed during the Pike development cycle.