Added functionality for updating and resetting compute quotas. (#214)

* Added functionality for updating and resetting compute quotas.
Unit and acceptance tests added.

* Forgot to add my latest changes.
Modified acceptance test to better find the tenant-id

* Improved test coverage.
And fixed a bug while doing this.

* Moved FillFromQuotaSet to acceptance test package
Refractored ToComputeQuotaUpdateMap()
diff --git a/openstack/compute/v2/extensions/quotasets/urls.go b/openstack/compute/v2/extensions/quotasets/urls.go
index e910376..4e15613 100644
--- a/openstack/compute/v2/extensions/quotasets/urls.go
+++ b/openstack/compute/v2/extensions/quotasets/urls.go
@@ -11,3 +11,11 @@
 func getURL(c *gophercloud.ServiceClient, tenantID string) string {
 	return c.ServiceURL(resourcePath, tenantID)
 }
+
+func updateURL(c *gophercloud.ServiceClient, tenantID string) string {
+	return getURL(c, tenantID)
+}
+
+func deleteURL(c *gophercloud.ServiceClient, tenantID string) string {
+	return getURL(c, tenantID)
+}
\ No newline at end of file