Fixes #246 Corrects the output of the image api get_all_images command

The `result` and `http_err_code` returned from the image api `get_all_images` command is incorrect.

Example output:
```
resource: "ProjectHanlon::Slice::Image"
command: "get_all_images"
result: "Created"
http_err_code: 201
errcode: 0
```

Should be:
```
resource: "ProjectHanlon::Slice::Image"
command: "get_all_images"
result: "Ok"
http_err_code: 200
errcode: 0
```

Fixes #246