Allows one to fetch a list of dependencies required by the bundle

@param {Function} done - receives err, dependencies:Array
function (done) {
        var dependencies = [],
            addPackageToDependencies = function (pkg) {
                dependencies.push(pkg.name);
            };

        this.bundler.on('package', addPackageToDependencies);

        return this.compile(function (err) {
            this.bundler.removeListener('package', addPackageToDependencies);
            return done(err, _.uniq(dependencies).sort());
        }.bind(this));
    }