fix(input): $asyncValidators should allow $parsers

After resolving the async validators, it should execute all parsers
on the viewValue before comparing it to the currentValue.

Currently, input[type=number] is not recognizing the end of the async validation because 
the comparison `currentValue === value` is comparing a number in `currentValue` against a string in `value`
https://github.com/angular/angular.js/blob/master/src/ng/directive/input.js#L1734