Gulp task to run protractor tests

Gulp task to start `protractor` tests. Before running tests it ensures webdriver is installed (`ensure_webdriver_standalone`) and starts it (`webdriver_standalone`).

Usage:
```
gulp test
```
It's non-deterministic of course. And I cannot guarantee that it will start < 1s in all cases. But I'm pretty sure it will in ~99%. However, I can rewrite it to parse output maybe it's good idea to do this when we see current method failing?