Make querying the API and parsing results a little easier.

Hey @theycallmeswift,

First of all kudos on the sweet npm package! It works well and makes querying the Grooveshark API a breeze.

Unfortunately the Grooveshark API docs are hard to navigate and can be a bit inconsistent. I tried to add a few more functions to the Grooveshark npm package to make querying the api and parsing the results a little easier and standardized (for example there's like 3 different formats for playlist info that the server returns). I didn't touch any of the original functions, only added a few more.

Let me know what you think and if there are any questions or concerns!

PS this is my first time using coffeescript. If anything looks weird or seems wrong feel free to correct.