Reintegrate jfryman/puppet-nginx#331 (upstream exports/collections)

- resurrecting jfryman/puppet-nginx#331 from @rainopik
- update (concat/stdlib) dependency version requirements based on current usage
- fix upstream tests to work with rainopik's changes in what was jfryman/puppet-nginx#331

p.s. Might I suggest that, prior to merging, anyone whom has any opinions on this (@leepa, @jfryman, @rainopik, @zxjinn, ??) take a look and reflect on whether or not this is at a point where it's ready?