Adds improvements to the Swift TempURL test

Adds one extra test, to cover the Temp-URL-Key-2 header. It also adds
the possibility to skip this test by adding an entry in the config
file.

Change-Id: I084e15b9f405bf880ffd4829f57b283cbc065afa
diff --git a/etc/tempest.conf.sample b/etc/tempest.conf.sample
index 567b85a..b9eb19e 100644
--- a/etc/tempest.conf.sample
+++ b/etc/tempest.conf.sample
@@ -711,7 +711,7 @@
 # Options defined in tempest.config
 #
 
-# Set to True if the container quota middleware is enabled
+# Set to True if the Container Quota middleware is enabled
 # (boolean value)
 #container_quotas=true
 
@@ -723,6 +723,10 @@
 # (boolean value)
 #crossdomain=true
 
+# Set to True if the TempURL middleware is enabled (boolean
+# value)
+#tempurl=true
+
 
 [volume-feature-enabled]