Initial integration of falisafe-plugin + selenium webdriver

As of [ZEPPELIN-75](https://zeppelin-project.atlassian.net/browse/ZEPPELIN-75) it becomes obvios that we need an end-to-end tests for zepplin.

One possible solution is to keep them in Java, so:

 1) To  run just **end-to-end tests** on any instance (set of click-through test in headless browser) we do:

     mvn integration-test -D url=http://localost:8080
  this assumes zeppelin is already running on given url, localhost could be set by default

 2) To **run zeppelin** (on localhost) + **end-to-end tests**:

     mvn verify

 3) To **package zeppelin** + **run it** from the packaged version + **end-to-end-tests**

     mvn verify -P using-packaged-distr



ZeppelinITCase.java is simple example, wich should eventually grow to automation of real demo scenario