reschedule just the relevant habit when showing a notification for it

And make sure not to schedule it for a possibly snoozed time, as that'd lead
to an infinite loop of scheduling it repeatedly for the current time.

uhabits-android/src/main/java/org/isoron/uhabits/receivers/ReminderController.java

@@ -65,7 +65,7 @@ public class ReminderController
                                long reminderTime)
     {
         notificationTray.show(habit, timestamp, reminderTime);
-        reminderScheduler.scheduleAll();
+        reminderScheduler.scheduleHabitAtReminder(habit);
     }
 
     public void onSnooze(@NonNull Habit habit, final Context context)

uhabits-android/src/test/java/org/isoron/uhabits/receivers/ReminderControllerTest.java

@@ -82,7 +82,7 @@ public class ReminderControllerTest extends BaseAndroidJVMTest
         Habit habit = mock(Habit.class);
         controller.onShowReminder(habit, Timestamp.ZERO.plus(100), 456);
         verify(notificationTray).show(habit, Timestamp.ZERO.plus(100), 456);
-        verify(reminderScheduler).scheduleAll();
+        verify(reminderScheduler).scheduleHabitAtReminder(habit);
     }
 
     @Test