added test for when stimulus starts with whitespace
added test for when stimulus starts with whitespace

this prevents passing the test by doing  stimulus[0] == ' '  for the silence response ('Fine. Be that way!').

exercism/xpython,de2Zotjes/xpython,rootulp/xpython,pombredanne/xpython,rootulp/xpython,mweb/python,jmluy/xpython,orozcoadrian/xpython,mweb/python,N-Parsons/exercism-python,jmluy/xpython,outkaj/xpython,exercism/python,orozcoadrian/xpython,behrtam/xpython,de2Zotjes/xpython,outkaj/xpython,wobh/xpython,wobh/xpython,exercism/python,oalbe/xpython,pombredanne/xpython,Peque/xpython,behrtam/xpython,N-Parsons/exercism-python,Peque/xpython,smalley/python,ZacharyRSmith/xpython,smalley/python,pheanex/xpython,pheanex/xpython,ZacharyRSmith/xpython,oalbe/xpython,exercism/xpython