Test page was created to be accessed by Se Nodes

Now when tests start, they start embedded server as well to show a test page
Se nodes are going to access. In this way we can test complex things like
native events because we can put anything we want on this page.

As for now tests check:
 - whether an element can be found on the page
 - Native Events (drag'n'drop) - fixes #1
 - Executing JavaSript by WebDriver
 - access to external resources from the Internet like JS, Images, etc.
Add missing files to the last commit
Downgraded Jetty version since 9.x requires Java 1.7

Because Java 1.7 is not that widely used yet and we don't require any new features
from Jetty 9.x, its version was dowgraded to be compatible with a wider audience.
Added an ability to use Proxy to get access to test page

- Proxy can be enabled by passing `-DPROXY_ENABLED` and using particular proxy
 configuration params like `-DhttpProxy=blah:8080`
- Added a WebDriverFactory in order to move preparation code out from tests