Add header in new files. Remove unused imports.

Contributes to CURA-5959.

resources/qml/ActionButton.qml

@@ -3,7 +3,6 @@
 
 import QtQuick 2.7
 import QtQuick.Controls 2.1
-import QtQuick.Layouts 1.3
 
 import QtGraphicalEffects 1.0 // For the dropshadow
 

resources/qml/PrimaryButton.qml

@@ -1,5 +1,7 @@
+// Copyright (c) 2018 Ultimaker B.V.
+// Cura is released under the terms of the LGPLv3 or higher.
+
 import QtQuick 2.2
-import QtQuick.Controls 1.1
 
 import UM 1.4 as UM
 import Cura 1.1 as Cura

resources/qml/SecondaryButton.qml

@@ -1,5 +1,7 @@
+// Copyright (c) 2018 Ultimaker B.V.
+// Cura is released under the terms of the LGPLv3 or higher.
+
 import QtQuick 2.2
-import QtQuick.Controls 1.1
 
 import UM 1.4 as UM
 import Cura 1.1 as Cura