(PUP-3151) Added acceptance test for External CA on Jetty

This commit adds an acceptance test which exercises External CA
functionality against a Jetty configuration.
(PUP-3157) Allow variable DNS name order in helpful error cert name test

This commit updates the
`helpful_error_message_when_hostname_not_match_server_certificate.rb`
test to allow for the order in which the DNS names are enumerated back
from the master server's certificate to be variable.  This allows the
test to not errantly fail depending upon the order in which the names
were actually signed into the certificate.
(PUP-3151) Removed newline from host_entry test fixture

This commit removes the newline character from the end of the host_entry
method in the acceptance test ExternalCertFixtures.  The presence of this
character was causing the jetty_external_root_ca.rb test, when run on
Debian, to not properly set the needed hostname entry into the
/etc/hosts file.
Merge pull request #3034 from camlow325/maint/master/PUP-3157-helpful-error-message-dns-name-order

(PUP-3157) Allow variable DNS name order in helpful error cert name test
Merge pull request #3028 from camlow325/maint/master/PUP-3151-jetty-external-root-ca-test

(PUP-3151) Added acceptance test for External CA on Jetty