Add Istanbul LCOV reporter

[hansl]

See https://github.com/angular/angular-cli/blob/master/addon/ng2/blueprints/ng2/files/config/karma.conf.js#L27

[angular-automatic-lock-bot]

This issue has been automatically locked due to inactivity.
Please file a new issue if you are encountering a similar or related problem.

Read more about our automatic conversation locking policy.

_{This action has been performed automatically by a bot.}