Missing 'active' Wheel group breaks Grouper

WheelAccessResolver and WheelNamingResolver try to instantiate the wheel group (if active). An exception is thrown if the group has not yet been created.

Should be possible to catch exception, log it, but continue. Need to check whether the Resolvers are created once (in which case crreating the wheel group won't magically cause it to work) or per GrouperSession (or similar, in which case it may start working on creation)