More specific types for ObjectStorage response object fields (#74)

* more accurate types for objectstorage response object fields (e.g. ContentLength: string -> in64)

* containers unit tests for new field types

* more specific types for accounts headers fields

* update accounts unit tests

* download header unmarshal method and unit test

* object results unmarshal methods
diff --git a/openstack/objectstorage/v1/containers/testing/fixtures.go b/openstack/objectstorage/v1/containers/testing/fixtures.go
index fe579d8..b68230a 100644
--- a/openstack/objectstorage/v1/containers/testing/fixtures.go
+++ b/openstack/objectstorage/v1/containers/testing/fixtures.go
@@ -103,7 +103,10 @@
 		th.TestHeader(t, r, "Accept", "application/json")
 
 		w.Header().Add("X-Container-Meta-Foo", "bar")
-		w.Header().Add("X-Trans-Id", "1234567")
+		w.Header().Set("Content-Length", "0")
+		w.Header().Set("Content-Type", "text/html; charset=UTF-8")
+		w.Header().Set("Date", "Wed, 17 Aug 2016 19:25:43 GMT")
+		w.Header().Set("X-Trans-Id", "tx554ed59667a64c61866f1-0058b4ba37")
 		w.WriteHeader(http.StatusNoContent)
 	})
 }
@@ -137,6 +140,15 @@
 		th.TestMethod(t, r, "HEAD")
 		th.TestHeader(t, r, "X-Auth-Token", fake.TokenID)
 		th.TestHeader(t, r, "Accept", "application/json")
+		w.Header().Set("Accept-Ranges", "bytes")
+		w.Header().Set("Content-Type", "application/json; charset=utf-8")
+		w.Header().Set("Date", "Wed, 17 Aug 2016 19:25:43 GMT")
+		w.Header().Set("X-Container-Bytes-Used", "100")
+		w.Header().Set("X-Container-Object-Count", "4")
+		w.Header().Set("X-Container-Read", "test")
+		w.Header().Set("X-Container-Write", "test2,user4")
+		w.Header().Set("X-Timestamp", "1471298837.95721")
+		w.Header().Set("X-Trans-Id", "tx554ed59667a64c61866f1-0057b4ba37")
 		w.WriteHeader(http.StatusNoContent)
 	})
 }