Fix wrong aliases at Fog::Volume::SakuraCloud::Archive

Fix Bug: archives returns nil.

```
 volume.archives
=> [  <Fog::Volume::SakuraCloud::Archive
    id=nil,
    name=nil
  >,
-- snip --
```

Expect below.

```
=> [  <Fog::Volume::SakuraCloud::Archive
    id="112500514887",
    name="CentOS 5.10 64bit (基本セット)"
  >,
-- snip --
```