Archlinux support added

only change needed service_name needed to be a variable across
distributions

rabbitmq_spec.rb needs to be refactored archlinux needs it
own testing...
updated spec file for archlinux
changed service to a named variable service
because of archlinux change in service name
make use of the user and password parameters

Prior to this patch the exchange creation will fall back to guest/guest, who
may not be an an admin user.

The type already takes the credentials, all we do here is pass them on.
Merge pull request #123 from richardc/exchange_authentication

make use of the user and password parameters
Merge pull request #107 from aboe76/archlinux-support

Archlinux support added