Add SSL to each proxy_get test

All tests can be run with:

./riak_test -c foo -t replication2_pg:test_basic_pg_mode_repl13,
etc

-t replication2_pg:test_basic_pg_mode_mixed,
-t replication2_pg:test_12_pg_mode_repl12,
-t replication2_pg:test_12_pg_mode_repl_mixed,
-t replication2_pg:test_mixed_pg,
-t replication2_pg:test_multiple_sink_pg,
-t replication2_pg:test_bidirectional_pg,
-t replication2_pg:test_pg_proxy,

-t replication2_pg:test_basic_pg_mode_repl13_ssl,
-t replication2_pg:test_basic_pg_mode_mixed_ssl,
-t replication2_pg:test_12_pg_mode_repl12_ssl,
-t replication2_pg:test_12_pg_mode_repl_mixed_ssl,
-t replication2_pg:test_mixed_pg_ssl,
-t replication2_pg:test_multiple_sink_pg_ssl,
-t replication2_pg:test_bidirectional_pg_ssl,
-t replication2_pg:test_pg_proxy_ssl

heads up to @seancribbs, I'll submit a Giddyup issue if these additional SSL tests are +1'd and merged.