Ensures compute_driver flag can be used by bdm

Fixes bug 1063851 by moving compute_driver flag from
compute/manager.py to the global flags.py

Change-Id: I337795f6956050b398c39a8476e3c1e2b689c470
Signed-off-by: Chuck Short <chuck.short@canonical.com>

nova/compute/manager.py

@@ -86,12 +86,6 @@
                help="Where cached images are stored under $instances_path."
                     "This is NOT the full path - just a folder name."
                     "For per-compute-host cached images, set to _base_$my_ip"),
-    cfg.StrOpt('compute_driver',
-               default='nova.virt.connection.get_connection',
-               help='Driver to use for controlling virtualization. Options '
-                   'include: libvirt.LibvirtDriver, xenapi.XenAPIDriver, '
-                   'fake.FakeDriver, baremetal.BareMetalDriver, '
-                   'vmwareapi.VMWareESXDriver'),
     cfg.StrOpt('console_host',
                default=socket.gethostname(),
                help='Console proxy host to use to connect '

nova/flags.py

@@ -419,6 +419,11 @@ def _get_my_ip():
                 help='Whether to batch up the application of IPTables rules'
                      ' during a host restart and apply all at the end of the'
                      ' init phase'),
+    cfg.StrOpt('compute_driver',
+               help='Driver to use for controlling virtualization. Options '
+                   'include: libvirt.LibvirtDriver, xenapi.XenAPIDriver, '
+                   'fake.FakeDriver, baremetal.BareMetalDriver, '
+                   'vmwareapi.VMWareESXDriver'),
 ]
 
 FLAGS.register_opts(global_opts)