translate text: "subnet"/"subnet details"

When trying to create or update a subnet from the Networks
details page, the tab titles 'Subnet' and 'Subnet details'
are not showing as translated. This patch add the missing
underscore.

Change-Id: I48cd47e7ead3717d96e4808f41bf876a567c8052
Closes-Bug: #1254026

openstack_dashboard/dashboards/project/networks/subnets/workflows.py

@@ -37,7 +37,7 @@ class CreateSubnetInfoAction(network_workflows.CreateSubnetInfoAction):
                                      widget=forms.HiddenInput())
 
     class Meta:
-        name = ("Subnet")
+        name = _("Subnet")
         help_text = _('You can create a subnet associated with the '
                       'network. Advanced configuration are available '
                       'at "Subnet Detail" tab.')
@@ -118,7 +118,7 @@ class UpdateSubnetInfoAction(CreateSubnetInfoAction):
                                     initial=False, required=False)
 
     class Meta:
-        name = ("Subnet")
+        name = _("Subnet")
         help_text = _('You can update a subnet associated with the '
                       'network. Advanced configuration are available '
                       'at "Subnet Detail" tab.')
@@ -139,7 +139,7 @@ class UpdateSubnetDetailAction(network_workflows.CreateSubnetDetailAction):
                                        required=False)
 
     class Meta:
-        name = ("Subnet Detail")
+        name = _("Subnet Detail")
         help_text = _('You can specify additional attributes for the subnet.')