Add spec/fixtures/modules/*/lib to the rspec $LOAD_PATH to handle custom providers in the catalog

This helps address autoload issues in rspec-puppet that would otherwise be handled by pluginsync

    1) role::puppetmaster
        Failure/Error: should contain_class 'profile::puppetmaster' }
        Puppet::Error:
        Could not autoload puppet/type/yaml_setting: Could not autoload puppet/provider/yaml_setting/mapped: cannot load such file -- puppetx/filemapper on node kiwi
        # ./spec/classes/role/puppetmaster_spec.rb:5:in `block (2 levels) in <top (required)>'
Enable rspec-puppet tests for the puppetmaster profile and role