Run tests in randomized order

[radoslav06]

The google test framework has very handy option to run tests in a randomized order (with optional number of repetitions). This can reveal problems with hidden tests and/or test fixtures dependencies. I cannot find a similar feature in Ceedling, so I guess it is a feature request then :)

Here's a reference to google test docs (search for "Shuffling the Tests"): http://google.github.io/googletest/advanced.html