MWEB-979 Watcher and server runner

@RafLeszczynski @hakubo Please check if workaround in `gulp/options/dev.js` is acceptable. It worked fine while smoke tested.
Or even [cache-buster](http://www.adopsinsider.com/ad-ops-basics/what-is-a-cache-buster-and-how-does-it-work/) ;) Yeah, if you can let's go with camel case. It's an object field but I think it'll be nice to follow [variables name convention](https://github.com/Wikia/guidelines/blob/master/JavaScript/CodingConventions.md#variables) :bow: