Added ability to mention item type

For example, this:

    var pace = require('pace')({
        total: 6838,
        itemType: 'points'
    });

will result in this:
![screen shot 2013-08-30 at 5 30 04 pm](https://f.cloud.github.com/assets/370976/1060850/7c1b676c-11bc-11e3-9899-38d52047cd5d.png)