change all time fields to have type time.Time (#190)

* add Volume.Unmarshal

* add volumetenants.VolumeExt.Unmarshal

* create servers.Server time.Time fields

* json.Unmarshal can correctly handle time.RFC3339 (Server time fields)

* add v3 Token UnmarshalJSON method

* check for empty string when unmarshaling time

* add Member UnmarshalJSON

* v3 tokens.Token ExtractInto

* v3 trust.Trust UnmarshalJSON

* time.Time fields swift response objects

* time.Time fields for orchestration response objects

* time.Time fields for shared file systems response objects

* if we don't use pointers for the custom time fields, we don't need to check if they're nil

* style guide fixes: 'r' for receiver, 's' for struct

* remove unnecessary pointers from UnmarshalJSON methods
diff --git a/openstack/identity/v3/extensions/trusts/results.go b/openstack/identity/v3/extensions/trusts/results.go
index 3d3c7f2..bdd8e84 100644
--- a/openstack/identity/v3/extensions/trusts/results.go
+++ b/openstack/identity/v3/extensions/trusts/results.go
@@ -1,7 +1,5 @@
 package trusts
 
-import "github.com/gophercloud/gophercloud/openstack/identity/v3/tokens"
-
 type TrusteeUser struct {
 	ID string `json:"id"`
 }
@@ -19,11 +17,6 @@
 	RedelegationCount  int         `json:"redelegation_count"`
 }
 
-type Token struct {
-	tokens.Token
-	Trust Trust `json:"OS-TRUST:trust"`
-}
-
 type TokenExt struct {
-	Token Token `json:"token"`
+	Trust Trust `json:"OS-TRUST:trust"`
 }