Support disabling server pausing for compute API

This adds a togglable compute feature for pause/unpause.

The Docker driver does not currently support this feature.

Change-Id: I6f5f1f4624e34801aa52def7450e65716073fc65
diff --git a/etc/tempest.conf.sample b/etc/tempest.conf.sample
index eb2340a..eb8d458 100644
--- a/etc/tempest.conf.sample
+++ b/etc/tempest.conf.sample
@@ -347,6 +347,9 @@
 # Does the test environment support resizing? (boolean value)
 #resize=false
 
+# Does the test environment support pausing? (boolean value)
+#pause=true
+
 # Does the test environment support live migration available?
 # (boolean value)
 #live_migration=false