(maint) Adjust new environment tests to work with PE

The changes to these tests are in two main categories:

1) Changes to file owner and group to use beaker host references so that
correct user/group settings are obtained regardless of whether a FOSS or
PE run is being performed.  Also changes to permissions to be more
permissive for group so that the puppet system user running under
Passenger can access key files.

2) Changes to basemodulepath to ensure that the modules PE master needs
to run under its /opt site module directory are always present.

In addition a few cases had to be exempted on PE altogether, notably
tests which were testing the effect of commandline environment settings.
Since running a PE master with commandline settings would require
modifying it's rack config.ru file, these tests make little sense in
this context.
(maint) Fix problems when rspec-puppet and rspec-helper are both used

This fixes a problem that arises when there is more than one
puppet test infrasturcutre "orchestrator"; e.g. rspec-puppet and
rspec-helper. They both add calls to the TestHelper and this ends up
setting up and tearing down the puppet environment for each test.

This problem has existed for a long time, but was noticed when using the
new mark/rollback to ensure test consistency.

The fix os to add a re-entrance check for before_each and after_each to
ensure that they only do the job once even if registered to be called
a number of times.
Merge pull request #2682 from kylog/issue/pup-2610-make-test_helper-reentrant

(maint) Fix problems when rspec-puppet and rspec-helper are both used
Merge pull request #2681 from jpartlow/maint/stable/environment-acceptance-fixes-for-pe

(maint) Adjust new environment tests to work with PE