Test warning: ConditionalLayout cannot be activated without a container

We need to remove all the warnings from the test suite, so that when a new warning appears we can tell if it's a real problem or something we can safely ignore. Currently there are too many warnings when running make check, and they might be hiding real bugs.

There are three warnings on tst_Layouts::testCase_PositioningOnLayoutChange():

QWARN : tst_Layouts::testCase_PositioningOnLayoutChange() file:///home/elopio/workspace/canonical/ubuntu-ui-toolkit/trunk/tests/unit_x11/tst_layouts/PositioningOnLayoutChange.qml:42:13: QML ConditionalLayout: ERROR: no container specified for layout "landscape". ConditionalLayout cannot be activated without a container.
QWARN : tst_Layouts::testCase_PositioningOnLayoutChange() file:///home/elopio/workspace/canonical/ubuntu-ui-toolkit/trunk/tests/unit_x11/tst_layouts/PositioningOnLayoutChange.qml:42:13: QML ConditionalLayout: WARNING: Cannot activate layout "landscape" with no container specified. Falling back to default layout.
QWARN : tst_Layouts::testCase_PositioningOnLayoutChange() file:///home/elopio/workspace/canonical/ubuntu-ui-toolkit/trunk/tests/unit_x11/tst_layouts/PositioningOnLayoutChange.qml:42:13: QML ConditionalLayout: WARNING: Cannot activate layout "landscape" with no container specified. Falling back to default layout.

There are three warnings on tst_Layouts::testCase_CurrentLayoutChange():

QWARN : tst_Layouts::testCase_CurrentLayoutChange() file:///home/elopio/workspace/canonical/ubuntu-ui-toolkit/trunk/tests/unit_x11/tst_layouts/CurrentLayoutChange.qml:30:13: QML ConditionalLayout: ERROR: no container specified for layout "portrait". ConditionalLayout cannot be activated without a container.
QWARN : tst_Layouts::testCase_CurrentLayoutChange() file:///home/elopio/workspace/canonical/ubuntu-ui-toolkit/trunk/tests/unit_x11/tst_layouts/CurrentLayoutChange.qml:35:13: QML ConditionalLayout: ERROR: no container specified for layout "landscape". ConditionalLayout cannot be activated without a container.
QWARN : tst_Layouts::testCase_CurrentLayoutChange() file:///home/elopio/workspace/canonical/ubuntu-ui-toolkit/trunk/tests/unit_x11/tst_layouts/CurrentLayoutChange.qml:30:13: QML ConditionalLayout: WARNING: Cannot activate layout "portrait" with no container specified. Falling back to default layout.