Fix Fibonacci Heap Bug

[nishantc1527]

It has come to my attention that the Fibonacci Heap has a bug, specifically when you chain the extract min method. Here is a test that doesn't work:

    for(int i = 0; i < 100; i ++) {
        heap.insert(i);
    }

    int count = 0;

    while(!heap.isEmpty()) {
        assertEquals(count ++, heap.extractMin());
    }

It would be nice if you could fix it.

Points: 20