qtcamera: change pipeline start sequence so we can query pipeline caps
qtcamera: change pipeline start sequence so we can query pipeline caps

We first set the pipeline to paused, query the caps and try to construct
our resolutions. After that we can apply the settings of the mode and then
set the pipeline to playing.

We cannot apply the mode settings because it needs resolutions which we have not
yet obtained

mlehtima/cameraplus,alinelena/cameraplus,mlehtima/cameraplus,alinelena/cameraplus,foolab/cameraplus,alinelena/cameraplus,mlehtima/cameraplus,foolab/cameraplus,mlehtima/cameraplus,mer-hybris-kis3/cameraplus,mer-hybris-kis3/cameraplus,foolab/cameraplus,mer-hybris-kis3/cameraplus,foolab/cameraplus,alinelena/cameraplus,mer-hybris-kis3/cameraplus