prepare for extension with new services

I added/changed a few lines to store the config passed to the functions in order to able to extend the services with new ones.

For example via this change I can easily add this:

	linkedin.people.picture = function(cb) {
		this.createCall('GET', 'people/~/picture-urls::(original)', cb)(this.config);
	}.bind( linkedin.people );

having a new profile image downloader function.