turn a node style callback into a promise based one
npm install lie-denodify
var denodify = require'lie-denodify';
takes as an argument a function which has a callback as it's last argument, returns a function that acts identically except it returns a promise instead of taking a callback and that arguments passed to the function may be promises as well
As a second argument it can take an object to call the function as a method of, if omitted calls it in the same context that the function was called (i.e. like normal).