Include Framework Element API for TestBench in the project (#8014)
This makes it possible to use the latest Element classes in the
framework tests and to simplify the build process.
The license for the included element classes are changed to Apache2
Some element methods have been integrated into TestBench and are removed from the
framework element classes
Change-Id: I35c8bf272b7603127816595de8145e68500e22e5
Move and rename server classes which go into the compatibility package
* Use com.vaadin.v7
* Use the same class name as in Vaadin 7
* Use a "vaadin7-" declarative prefix for Vaadin 7 components
Change-Id: I19a27f3835b18980b91a4f8f9464b2adde1a5fd5