aheckmann/gm — pull request #190 by tornillo (2013-07-15 14:46:01+00:00)
Title: Identify custom format

Usage:
```javascript
gm('./examples/imgs/original.jpg').format({ custom: '%f: %m, %wx%h' }, function (err, meta) {
console.log(meta);
});

log:
original.jpg: JPEG, 460x155
```

It's very useful for get only specified fields of metadata (custom string format, delimiters, etc.) without verbose "slow" option.