refactor($Grunt test task): Add headless + VM test

All saucelabs-based tests have  been removed/commented-out.
A single Grunt task, test, is used to run tests now.
This test can run IE browsers (in virtual machines), locally installed browsers,
and/or headless (PhantomJS) browsers.

This task can take a few "browser groups" which already have lists of browsers
hard-coded in the task.

    grunt test:server -- runs a server with no browsers for manual testing.
    grunt test:travis -- runs headless unit tests on travis
    grunt test:headless -- runs headless unit tests using PhantomJS
    grunt test:ie -- Runs IEVMs-based tests automatically
    grunt test:ios -- Runs iOS simulator tests. Not working on Xcode 5.
    grunt test:all -- Test all browsers.

or you can pass in specific browsers to test:

    grunt test:Firefox
    grunt test:Chrome
    grunt test:Firefox,Chrome,Safari
    grunt test:IE7 - WinXP

You can also pass in regular Karma command-line arguments which will override
any settings in configuration files.

    grunt test:all --single-run --no-auto-watch
fix(Gruntfile): Remove iOS simulator test until fixed in xdissent/iosctrl