Remove hashie dependency

TCLIConnection constructor had a separate check for Hashie (third-party hash implementation) w/o making sure Hashie classes are actually available. So this check would blow up in any project, that didn't use Hashie gem.

I've replaced it with a simple piece of code that would convert all incoming hash keys to symbols just as it would happen before. Hashie mimicks normal Hash class behaviour so it should work for them as well.