Fail gracefully

Empty galleries return `["no results"]`. Both jq and json2csv fail miserably:

```
114
jq: error: Cannot index array with string

undefined:0

^
SyntaxError: Unexpected end of input
    at Object.parse (native)
    at Socket.<anonymous> (/usr/local/Cellar/node/0.8.16/lib/node_modules/json2csv/bin/json2csv.js:54:25)
    at Socket.EventEmitter.emit (events.js:117:20)
    at _stream_readable.js:920:16
    at process._tickCallback (node.js:415:13)
```