shutdown:handle mult-screen

solve:
    1.new window in full screen for drawing background in full screen
    2.the container only show in primary screen
    3.add listen gkt 'monitors-changed' signal and then:
        a. move container to primary screen
        b. it will auto-redraw the background in window in lib/background.c

TODO in another CL:
    1.add listen to mouse-screen-changed signal and then:
      a.move container to the screen moved

tower:https://tower.im/projects/8f19f0bf0e754f0b82ef2c24bc230973/todos/c62e1f11600140bcbe66941e1304bfff/

Change-Id: I063c14633a11d6fba14399815bccae3f3f9918cd