[Feature] allow custom modal class and spotlight classes

[satyapramodh]

Template.foo.helpers({
  options: {
    id: "myCoolTutorial",
    steps: tutorialSteps,
    emitter: new EventEmitter(),
    modalClass: "myFancyModalClass",
    spotlightClass: "myFancySpotlightClass",
    onFinish: function() { /* make the tutorial disappear */ }
  }
});

Allow for custom classes to override the default ui.

[mizzao]

Hi @whiteBeatle - I apologize for the extremely long delay on this.

I have been too busy to maintain this project effectively, so I gave you commit access to make any changes you'd like. It would be nice to follow the style used by the rest of the code and add some tests to this patch, if possible.

If you'd like permission to publish the package to Meteor as well, please send me your Meteor developer username.