Add IPv6 support to scenario tests

This patch complements I4ca727f92618998242af18908bbbda6bb5f86303
by adding IPv6 functionality to scenario tests.

Also, as described in I4ca727f92618998242af18908bbbda6bb5f86303,
this change is also adding a new test config option to override
NFS access rules.

Change-Id: Id8b005cdd429d53a75624885fe7ca795746c3ede
diff --git a/manila_tempest_tests/config.py b/manila_tempest_tests/config.py
index e33dba8..4e6c99b 100644
--- a/manila_tempest_tests/config.py
+++ b/manila_tempest_tests/config.py
@@ -82,6 +82,10 @@
     cfg.StrOpt("username_for_user_rules",
                default="Administrator",
                help="Username, that will be used in user tests."),
+    cfg.StrOpt("override_ip_for_nfs_access",
+               help="Forces access rules to be as specified on NFS scenario"
+                    " tests. This can used for working around multiple "
+                    "NATs between the VMs and the storage controller."),
     cfg.ListOpt("enable_ro_access_level_for_protocols",
                 default=["nfs", ],
                 help="List of protocols to run tests with ro access level."),
@@ -244,4 +248,8 @@
     cfg.IntOpt("share_size",
                default=1,
                help="Default size in GB for shares created by share tests."),
+    cfg.BoolOpt("run_ipv6_tests",
+                default=False,
+                help="Enable or disable running IPv6 tests."),
+
 ]