Improve CVE 2013 1654 SSLv2 Downgrade Master test

Previously we were only checking for the applicability of the master
(since we're testing the master), but we run the check from an agent.
This ensures the agent we run the check from has the necessary openssl
client for the test.

Signed-off-by: Justin Stoller <justin@puppetlabs.com>
Merge branch 'justinstoller-maint/2.7.x/improve_downgrade_master_test' into 2.7.x

* justinstoller-maint/2.7.x/improve_downgrade_master_test:
  Improve CVE 2013 1654 SSLv2 Downgrade Master test

closes #1548