minor improvements

[mrose17]

1. if there is an error in require('./categories').all(), invoke the callback with null
2. figure out an easy way to generate var rules in index.js, perhaps by having it do a require(...) on a file that is generated on commit

[aekeus]

The callback currently takes two parameters, the first is the err object and the second is the array of rules. Would you like the array of rules parameter to be null when an error occurs?

[mrose17]

i thought there was only one parameter. in that case: when an error occurs, please use (err, null) thanks!