server personality + user_data support

adds basic support for server 'personalities' and 'user_data' as per [jumpgate issue 32](https://github.com/softlayer/jumpgate/issues/32) and [jumpgate issue 31](https://github.com/softlayer/jumpgate/issues/31)

The content is passed through as JSON structured data as discussed in the jumpgate issues mentioned above.

For example:
```
curl https://api.service.softlayer.com/rest/v3/SoftLayer_Resource_Metadata/UserMetadata.txt
{"user_data": "W0RFRkFVTFRdCmd1ZXN0X2lkPTEKdGVuYW50X2lkPIIsd77", "metadata": {"key2": "val2", "key1": "val1"}}
```