Attempt to test live_migration by default

Now that we are starting to try testing multi node devstack we want to
test live_migration. In single node setups the live_migration tests will
be skipped  since the tests make sure there are at least two compute nodes first.

Change-Id: I8e8a940a6eb3fa28adafb1035c549eb6d572baac
diff --git a/etc/tempest.conf.sample b/etc/tempest.conf.sample
index 9a9952d..2e4862d 100644
--- a/etc/tempest.conf.sample
+++ b/etc/tempest.conf.sample
@@ -429,7 +429,7 @@
 
 # Does the test environment support live migration available? (boolean
 # value)
-#live_migration = false
+#live_migration = true
 
 # Does the test environment support pausing? (boolean value)
 #pause = true
diff --git a/tempest/config.py b/tempest/config.py
index 6e8238a..d1615c0 100644
--- a/tempest/config.py
+++ b/tempest/config.py
@@ -312,7 +312,7 @@
                 default=True,
                 help="Does the test environment support suspend/resume?"),
     cfg.BoolOpt('live_migration',
-                default=False,
+                default=True,
                 help="Does the test environment support live migration "
                      "available?"),
     cfg.BoolOpt('block_migration_for_live_migration',