update stockfish options

* Stockfish has changed their options. They are documented at
  http://support.stockfishchess.org/kb/advanced-topics/engine-parameters
* You can see the option source code at
  https://github.com/official-stockfish/Stockfish/blob/master/src/ucioption.cpp#L55
* Since they are in flux, we should probably not bail out every
  time we encounter an inability to set an option; this code prints
  and error rather than throwing a ValueError upon finding an option
  that it cannot set
* The current stable version of stockfish has a "Contempt Factor"
  option but the current development version has renamed it to
  "Contempt". This patch just attempts each name on the assumption
  that one of them will succeed
* The rand option is greatly simplified by the fact that there now
  appears to be only one option that can reasonably be altered
  to slightly change the engines behavior, the `Contempt` parameter
Merge pull request #4 from llimllib/master

Update Stockfish options and allow graceful failing when options are misnamed.