SpinBox: hide VKB when appropriate

Change-Id: I18eff3eb2b932b814d0808079c7ddf3b3bfaaf53
Reviewed-by: Mitch Curtis <mitch.curtis@digia.com>

src/controls/SpinBox.qml

@@ -309,6 +309,8 @@ Control {
         }
         onAccepted: {
             input.text = validator.text
+            Qt.inputMethod.commit()
+            Qt.inputMethod.hide()
             selectValue()
         }