Reset bus before each rack middleware spec
Reset bus before each rack middleware spec

Also, remove unused variable in after block.

MadBomber/message_bus,MadBomber/message_bus,SamSaffron/message_bus,cannikin/message_bus,nathanstitt/message_bus,cannikin/message_bus,cannikin/message_bus,nathanstitt/message_bus,SamSaffron/message_bus,MadBomber/message_bus,nathanstitt/message_bus