fix(input): ensure ngModelWatch() triggers second digest pass when appropriate

Due to an earlier change, ngModelWatch() no longer returns a value to the
caller. This means the digest loop has no way to tell if the watch actually
modified anything and so can not schedule another pass.

This means any watches that watch form or model controller changes
(e.g. watches on form.$valid) that are scheduled prior to an ngModelWatch()
will not be able to see any changes made therin.

This commit fixes this behavior by returning the latest evaluated ng-model
value.

Closes #5258
Closes #5282
chore(travis): move checks from before_scripts to scripts

If jshint (or any other ci-check) fails, Travis marks the build as "Errored" which I don't think is desider:
https://travis-ci.org/angular/angular.js/builds/14938896
Merge branch 'master' of https://github.com/angular/angular.js
componentizd!