Fix crash on notification

[tiwiz]

With API < 23, the notification crashes with this logacat

FATAL EXCEPTION: main
Process: it.droidconit.dummiladisciassette, PID: 8283
java.lang.NoSuchMethodError: No virtual method getColor(ILandroid/content/res/Resources$Theme;)I in class Landroid/content/res/Resources; or its super classes (declaration of 'android.content.res.Resources' appears in /system/framework/framework.jar)
at net.squanchy.notification.NotificationCreator.createDefaultBuilder(NotificationCreator.java:97)
at net.squanchy.notification.NotificationCreator.createFrom(NotificationCreator.java:50)
at net.squanchy.notification.NotificationCreator.createFrom(NotificationCreator.java:41)
at net.squanchy.DebugActivity.createAndNotifyTalksCount(DebugActivity.java:62)
at net.squanchy.DebugActivity.testSingleNotification(DebugActivity.java:50)
at net.squanchy.DebugActivity.lambda$onCreate$0(DebugActivity.java:38)
at net.squanchy.DebugActivity$$Lambda$1.onClick(Unknown Source)
at android.view.View.performClick(View.java:4785)
at android.view.View$PerformClick.run(View.java:19858)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:155)
at android.app.ActivityThread.main(ActivityThread.java:5696)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1028)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:823)