Cards: add a simple shadow

Signed-off-by: Christophe Chapuis <chris.chapuis@gmail.com>
Stub tests: implement a fake "palm://com.palm.applicationManager/getAppInfo" answer

Signed-off-by: Christophe Chapuis <chris.chapuis@gmail.com>
Rearchitecture of the window manager and the card view

Signed-off-by: Christophe Chapuis <chris.chapuis@gmail.com>