make spec test for rabbitmq::repo::rhel run

The file spec/classes/rabbitmq_repo_rhel.rb was missing _spec in its
filename to let the spec tests for rabbitmq::repo::rhel run.
extra apt pinning stuff is not necessary
fetch rabbitmq public signing key from rabbitmq.com
add spec tests for rabbitmq::repo::apt
remove superfluous file spec/fixtures/manifests/site.pp
fix to make it run in puppet 3 as HOME is stripped, and erl needs HOME set
fix to make it run in puppet 3 as HOME is stripped, and erl needs HOME set
Merge branch 'master' of https://github.com/Mayflower/puppetlabs-rabbitmq
Merge branch 'master' of https://github.com/gergnz/puppetlabs-rabbitmq