update bundle - we shall bundle rack 1.4.2 in next release
update appraisal to latest rails versions
reproduce #139 (incompatibility with JRuby 1.7)
Use correct version of print_backtrace
tune backtrace capture fix 700cf738bf9aaf73 to support 1.5
as we might still work with 1.5.6 although officially we won't support anything before the JRuby 1.6 line (closes #139)
yet some more (stupid) latest rspec magic