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/openstack/dns/v2/zones/doc.go b/openstack/dns/v2/zones/doc.go
new file mode 100644
index 0000000..1302cb9
--- /dev/null
+++ b/openstack/dns/v2/zones/doc.go
@@ -0,0 +1,6 @@
+// Package tokens provides information and interaction with the zone API
+// resource for the OpenStack DNS service.
+//
+// For more information, see:
+// http://developer.openstack.org/api-ref/dns/#zone
+package zones