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/accounts/testing/fixtures.go b/openstack/objectstorage/v1/accounts/testing/fixtures.go
index a265199..fff3071 100644
--- a/openstack/objectstorage/v1/accounts/testing/fixtures.go
+++ b/openstack/objectstorage/v1/accounts/testing/fixtures.go
@@ -16,6 +16,7 @@
 		th.TestHeader(t, r, "X-Auth-Token", fake.TokenID)
 
 		w.Header().Set("X-Account-Container-Count", "2")
+		w.Header().Set("X-Account-Object-Count", "5")
 		w.Header().Set("X-Account-Bytes-Used", "14")
 		w.Header().Set("X-Account-Meta-Subject", "books")
 		w.Header().Set("Date", "Fri, 17 Jan 2014 16:09:56 GMT")