[BUGFIX Beta] Makes sure you can't use unregistered helpers in templates
Add support for min & max on HTML 5 inputs

This will allow support of the min & max attributes on the `number` and
`range` input types from HTML5.
Merge pull request #3898 from bcardarella/bc-min-max-for-inputs

Add support for min & max on HTML 5 inputs
Merge pull request #3897 from twokul/missing-helper-message

[BUGFIX Beta] Makes sure you can't use unregistered helpers in templates
[BUGFIX beta] Ensure willMergeMixin is called on each Mixin.

Call `willMergeMixin` for each Mixin in the list. This allows you to
implement `willMergeMixin` for multiple mixins in the same object.

Unfortunately, `_super` cannot be used as it causes infinite recursion
in some cases. (https://github.com/emberjs/ember.js/issues/3523 and
https://github.com/emberjs/ember.js/pull/3683)