chore(validate-commit-msg.js): increase the max line limit for commit messages from 70 to 100
docs(rootScope): add example of using a listener function for $watch

Closes #4451
docs(ngClass): fix typo

Closes #4471
chore(grunt): add jshint to the test task

It is very easy to let jshint failures slip into the master build if
the jshint task is not part of the standard local grunt tasks.