(PUP-1676) Environmentpath acceptance test uses basemodulepath

Given that the Directories environment loader gets initialized with
basemodulepath, we have to adjust the master puppet.conf for
use_environment_from_environmentpath.rb to also use basemodulepath so
that we find globally installed modules.
Merge branch 'issue/master/pup-1676-basemodulepath-acceptance-fix'

* issue/master/pup-1676-basemodulepath-acceptance-fix:
  (PUP-1676) Environmentpath acceptance test uses basemodulepath