Moved and renamed 'simple knapsack'
Moved and renamed 'simple knapsack'

- Moved it down so simpler test cases precede it.
- Renamed it to 'example knapsack' since 'simple' is relative.
- Removed some trailing whitespace

rpottsoh/x-common,jmluy/x-common,jmluy/x-common,ErikSchierboom/x-common,petertseng/x-common,exercism/x-common,petertseng/x-common,ErikSchierboom/x-common,jmluy/x-common,rpottsoh/x-common,exercism/x-common