Circular owner associations

[burrows]

Allows for circular owner associations like the following:

var A = Basis.Model.extend('A', function() {
  this.hasMany('bs', 'B', {inverse: 'as', owner: true});
});

var B = Basis.Model.extend('B', function() {
  this.hasMany('as', 'A', {inverse: 'bs', owner: true});
});

Previously this would have caused the #hasErrors and #hasChanges methods to enter infinite loops. Simply made use of the detectRecursion utility method to detect the loops and abort them.