Make erlang_additional_packages installation compatible with ansible 2.x

[saaji]

This fix addresses the

failed: [hostname] (item=[u'erlang_additional_packages']) => {"failed": true, "item": ["erlang_additional_packages"], "msg": "No package matching 'erlang_additional_packages' is available"}

issue with solution provided in ansible/ansible#14032

[mtpereira]

Hello @saaji,

I've just fixed this on the 3.0.0 version of this role. Sorry for not merging your solution but I prefer to keep it simple and only support one Ansible version.

Thank you!