MCO-489 Disable SSLv2 negotiation and ciphers

Here we redefine the constructor of OpenSSL::SSL::SSLContext to default to
disable SSLv2 protocol negotiation and SSLv2 cipher suites.

This is copied pretty directly from the monkey-patching that puppet performs,
which was introduced in 52be0439 for #19151

https://github.com/puppetlabs/puppet/commit/52be043933d40aab3449214f2aa602ceb214f91e
MCO-489 Disable SSLv3 handshakes globally

Here we extend the monkey-patching of OpenSSL::SSL::SSLContext to also
disable SSLv3 protocol negotiation.
Merge pull request #253 from richardc/MCO-489-disable_sslv2_sslv3_by_default_stable

MCO-489 disable sslv2 and sslv3 by default