Merge lastest commit from homescreen-2017

Merge lastest commit from homescreen-2017

    Merge two lastest commit from homescreen-2017.

1)  StatusBarModel: fix QQmlContext reference
    Fix missing include
    Bug-AGL: SPEC-1628

2)  Improve output of multiple screen resolution
    To improve output on various monitor with various resolution,
    use scale_factor from WM to fit various screen resolution.
    Bug-AGL: SPEC-1568, SPEC-1569, SPEC-1611

Change-Id: I71a6c87187c2b0b81bb0ed10cc8779032aa19300
Signed-off-by: Matt Porter <mporter@konsulko.com>Y
Signed-off-by: Tadao Tanikawa <tanikawa.tadao@jp.panasonic.com>
Signed-off-by: zheng_wenlong <wenlong_zheng@nexty-ele.com>