os-tenant-networks

This commit adds support for the os-tenant-networks extension.
diff --git a/openstack/compute/v2/extensions/tenantnetworks/results.go b/openstack/compute/v2/extensions/tenantnetworks/results.go
new file mode 100644
index 0000000..8050092
--- /dev/null
+++ b/openstack/compute/v2/extensions/tenantnetworks/results.go
@@ -0,0 +1,68 @@
+package tenantnetworks
+
+import (
+	"github.com/mitchellh/mapstructure"
+	"github.com/rackspace/gophercloud"
+	"github.com/rackspace/gophercloud/pagination"
+)
+
+// A Network represents a nova-network that an instance communicates on
+type Network struct {
+	// CIDR is the IPv4 subnet.
+	CIDR string `mapstructure:"cidr"`
+
+	// ID is the UUID of the network.
+	ID string `mapstructure:"id"`
+
+	// Name is the common name that the network has.
+	Name string `mapstructure:"label"`
+}
+
+// NetworkPage stores a single, only page of Networks
+// results from a List call.
+type NetworkPage struct {
+	pagination.SinglePageBase
+}
+
+// IsEmpty determines whether or not a NetworkPage is empty.
+func (page NetworkPage) IsEmpty() (bool, error) {
+	va, err := ExtractNetworks(page)
+	return len(va) == 0, err
+}
+
+// ExtractNetworks interprets a page of results as a slice of Networks
+func ExtractNetworks(page pagination.Page) ([]Network, error) {
+	networks := page.(NetworkPage).Body
+	var res struct {
+		Networks []Network `mapstructure:"networks"`
+	}
+
+	err := mapstructure.WeakDecode(networks, &res)
+
+	return res.Networks, err
+}
+
+type NetworkResult struct {
+	gophercloud.Result
+}
+
+// Extract is a method that attempts to interpret any Network resource
+// response as a Network struct.
+func (r NetworkResult) Extract() (*Network, error) {
+	if r.Err != nil {
+		return nil, r.Err
+	}
+
+	var res struct {
+		Network *Network `json:"network" mapstructure:"network"`
+	}
+
+	err := mapstructure.Decode(r.Body, &res)
+	return res.Network, err
+}
+
+// GetResult is the response from a Get operation. Call its Extract method to interpret it
+// as a Network.
+type GetResult struct {
+	NetworkResult
+}