Version bump of v0.1.0

Implementation to make `Model.sync` private. This fits with the overall goal of Modella to abstract sync layer stuff away from the developer...

Added a `Model.useSync` method that emits a `syncSet` event which is helpful for not requiring order dependency on plugin loading. E.g. without this this event, the following is impossible: 

    User.use(validators); 
    User.attr('someField', {unique: true}) 
    User.use(mongo)

You can see how I used `modella` v0.1.0 new events to solve this in the latest version of [modella/validators](http://github.com/modella/validators).

Along similar lines, I also added an `attrAdded` event which gets called on `Model.attr`. This is helpful for plugins that use options when an event is added, such as [modella/validators](http://github.com/modella/validators). Without this, the following would break since we only evaluate at `Model.use(plugin)`:

    var User = modella('user');
    User.use(validators);
    User.attr('name', { required: true } );

All and all, I think that these changes + all the previous changes warrant enough to do a minor version bump. Let me know your thoughts @matthewmueller