Adds tests covering Swift's container quotas middleware

The execution of the tests is conditional to a setting declared
in the config file (container_quotas_available by default to True).

There are 3 tests:
 + User uploads an object smaller than the quota successfully
 + User fails to upload an object larger than the bytes quota
 + User fails to upload many objects that exceeds the count limit

Closes-Bug: 1225891
Change-Id: Id93f6c3628624f115a3c7a91de8a8e7894003f3f
diff --git a/etc/tempest.conf.sample b/etc/tempest.conf.sample
index cd57354..fc1b0af 100644
--- a/etc/tempest.conf.sample
+++ b/etc/tempest.conf.sample
@@ -268,6 +268,8 @@
 container_sync_interval = 5
 # Set to True if the Account Quota middleware is enabled
 accounts_quotas_available = True
+# Set to True if the Container Quota middleware is enabled
+container_quotas_available = True
 
 # Set operator role for tests that require creating a container
 operator_role = Member