Maint: (#18294) Update docs for ip property of Zone type (allows defrouters since 2.6)

Per Redmine 18294, the Zone type has allowed specifying default routers as part
of the IP string since at least 2.6 -- see Redmine 4296 for deets. This commit
updates the doc string to show how to do that.
(PUP-1144) Make future parser accept $_private

This removes validation of QualifiedName (they must be validated
differently depending on where they appear). Variables were bit
by this too restrictive validation rule.
(PUP-1144) Fix up failing tests (pending new/better validation)

Two tests that expected validation to fail did not get triggered
because the too strict validation was removed. It needs to be replaced
with a different better validation. Such validation should be added
in 3.5 (too much work for 3.4) - instead, just accepting potentially
faulty names (they still have to lex correctly).
(PUP-1144) Make variable name checking stricter

The fix for PUP-1144 relaxed the rules for variable checking.
This reintroduces checking but done right. It is now possible to
start the *first* name segment with an underscore. Subsequent
segments must start with a lower case letter.

Legal:

* $_a
* $::_a
* $aA
* $aA::aA

Illegal:

* $a::_a
* $A
* $a::A
(PUP-672) TrustedInformation handles a nil certificate.

Acceptance caught an issue with an external ca not passing the
certificate info in the request (the
acceptance/tests/external_ca_support/apache_external_root_ca.rb does
this because its SSLOptions does not have +ExportCertData in
acceptance/tests/external_ca_support/fixtures/httpd.conf).

So we are modifying the TrustedInformation class to handle a nil
certificate without failure, but issue an info level warning in the
logs.

This also modifies the acceptance test to ensure a teardown, as failure
to reach the clean up code is breaking following tests when the httpd
server gets left up as master.
Merge pull request #2220 from jpartlow/issue/master/pup-672-trusted-information-and-external-ca

(PUP-672) TrustedInformation handles a nil certificate.
(packaging) Update PUPPETVERSION to 3.4.2
Merge tag '3.4.2'

3.4.2

* tag '3.4.2':
  (packaging) Update PUPPETVERSION to 3.4.2
  (PUP-1144) Fix up failing tests (pending new/better validation)
  (PUP-1144) Make future parser accept $_private
(PUP-1120) Fix private key permissions for group read

Have the hostprivkey saved with 0640 permissions to allow
the service group to be able to read by other puppet services
like PuppetDB and Foreman.
Merge branch 'pr/2169'

* pr/2169:
  (PUP-1120) Fix private key permissions for group read

Closes GH-2169
Merge pull request #2134 from nfagerlund/docs_zone_defrouter

Maint: (#18294) Update docs for ip property of Zone type (allows defrouters since 2.6)