fix os name for windows 8.1

Error: 09:58:29.895 INFO - Default driver org.openqa.selenium.ie.InternetExplorerDriver registration is skipped: registration capabilities Capabilities [{platform=WINDOWS, ensureCleanSession=true, browserName=internet explorer, version=}] does not match with current platform: WIN8_1

BUT:
according to https://code.google.com/p/selenium/issues/detail?id=7516
barancev: BTW, platform matching for Win 8.1 is fixed in the trunk and the fix will be released in 2.43