e_client/e_policy: add maximize_type for maximizing window

e_client/e_policy: add maximize_type for maximizing window

There is a requirement to maximize window to full screen size.
In most cases, when the window request to maximize, it is maximized to a size exculuding
the obstacles(such as taskbar) area.
However, special apps such as home screen should be maximized to the size of the entire
screen.

So, we add a maximize_type in the E_Client structure to decide the maximize type.

Change-Id: Ifde8188b04a43c256f88439bdfac7e84086f1537