DNS Zones: List / Get (#271)

* Add Zone List / Get Support

* Addressing code review comments

* Adding v2 to DNS client

* List / Get unit tests plus updates to results for unit tests to work.

* DNS v2 List acceptance tests

* add failing unit test for dns v2 allpages

* Changing acceptance test for DNS v2 to use AllPages

* Adding empty zones.go file for package requirements

* Change ttl back to int

* DNS v2 Zones ListOpts
diff --git a/acceptance/openstack/dns/v2/zones.go b/acceptance/openstack/dns/v2/zones.go
new file mode 100644
index 0000000..5ec3cc8
--- /dev/null
+++ b/acceptance/openstack/dns/v2/zones.go
@@ -0,0 +1 @@
+package v2