Simplify bindings by using generics

Bindings class uses generic for bound objects, so Bindings subclasses
don't have to implement own add() method.

Signed-off-by: Jiří Janoušek <janousek.jiri@gmail.com>
Remove MediaKeys' dependency AppRunnerController

It currently depends only on GlobalKeybinder.

Signed-off-by: Jiří Janoušek <janousek.jiri@gmail.com>
Create Makefile for tests

Signed-off-by: Jiří Janoušek <janousek.jiri@gmail.com>