Fixed Problem with NullPointer

`java.lang.RuntimeException: Unable to start activity ComponentInfo{de.azapps.mirakelandroid/de.azapps.mirakel.main_activity.MainActivity}: java.lang.NullPointerException : at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2308)`
Fixed Nullpointer with Reminders

`java.lang.NullPointerException at de.azapps.mirakel.reminders.ReminderAlarm.onReceive(ReminderAlarm.java:78)`
Fixed Nullpointer in TaskFragment

`java.lang.NullPointerException at de.azapps.mirakel.main_activity.TaskFragment.onCreateView(TaskFragment.java:89)`
Handling when a list vanish while do something with a task
Handling IndexOutOfBoundsException when creating widget

`java.lang.IndexOutOfBoundsException at de.azapps.mirakel.widget.MainWidgetProvider.onUpdate(MainWidgetProvider.java:160)`
Cleaned up