Fixes model errors not being return by validate()
Fixes model errors not being return by validate()

Models that have a validate function and return errors in the format

  {field: 'error message'}

are being skipped. The error message is added to the field, but form.validate()
doesn't return the error, causing the form to appear valid.

Shinobi881/backbone-forms,dmil/backbone-forms,powmedia/backbone-forms,exussum12/backbone-forms,fonji/backbone-forms,fonji/backbone-forms,nareshv/backbone-forms,bryce-gibson/backbone-forms,wesvetter/backbone-forms,iabw/fork_of_backbone-forms,GabeIsman/backbone-forms,goodwall/backbone-forms,wesvetter/backbone-forms,Shinobi881/backbone-forms,exussum12/backbone-forms,ldong/backbone-forms,AlJohri/backbone-forms,powmedia/backbone-forms,wesvetter/backbone-forms,dmil/backbone-forms,AlJohri/backbone-forms,nareshv/backbone-forms,GabeIsman/backbone-forms,goodwall/backbone-forms,CashStar/backbone-forms,bryce-gibson/backbone-forms,ldong/backbone-forms,CashStar/backbone-forms,iabw/fork_of_backbone-forms